Compound, material for organic electroluminescent elements, organic electroluminescent element, and electronic device

ABSTRACT

A compound is represented by a formula (1) below, in which k is an integer of 0 or more, m is an integer of 1 or more, n is an integer of 2 or more. L is a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 30 ring carbon atoms, CN is a cyano group, and D 1  and D 2  are each independently represented by one of a formula (2), a formula (3) and formula (3x) below, D 1  and D 2  being optionally mutually the same or different.

TECHNICAL FIELD

The present invention relates to a compound, a material for an organicelectroluminescence device, an organic electroluminescence device, andelectronic equipment.

BACKGROUND ART

When voltage is applied to an organic electroluminescence device(hereinafter, occasionally referred to as an organic EL device), holesare injected from an anode to an emitting layer while electrons areinjected from a cathode to the emitting layer. The injected holes andelectrons are recombined in the emitting layer to form excitons. At thistime, singlet excitons and triplet excitons are generated at a ratio of25%:75% according to statistics of electron spin. In the classificationaccording to the emission principle, in a fluorescent EL device whichuses emission caused by singlet excitons, an internal quantum efficiencyof the organic EL device is believed to be limited to 25%. On the otherhand, it has been known that the internal quantum efficiency can beimproved up to 100% under efficient intersystem crossing from thesinglet excitons in a phosphorescent EL device which uses emissioncaused by triplet excitons.

A technology for extending a lifetime of a fluorescent organic EL devicehas recently been improved and applied to a full-color display of amobile phone, TV and the like. However, an efficiency of a fluorescentEL device is required to be improved.

Based on such a background, a highly efficient fluorescent organic ELdevice using delayed fluorescence has been proposed and developed. Forinstance, an organic EL device using TTF (Triplet-Triplet Fusion)mechanism that is one of mechanisms for delayed fluorescence has beenproposed. The TTF mechanism utilizes a phenomenon in which singletexcitons are generated by collision between two triplet excitons.

By using delayed fluorescence by the TTF mechanism, it is consideredthat an internal quantum efficiency can be theoretically raised up to40% even in fluorescent emission. However, as compared withphosphorescent emission, the fluorescent emission is still problematicon improving efficiency. Accordingly, in order to enhance the internalquantum efficiency, an organic EL device using another delayedfluorescence mechanism has been studied.

For instance, TADF (Thermally Activated Delayed Fluorescence) mechanismis used. The TADF mechanism utilizes a phenomenon in which inverseintersystem crossing from triplet excitons to singlet excitons isgenerated by using a material having a small energy gap (ΔST) betweenthe singlet level and the triplet level. An organic EL device with useof the TADF mechanism is disclosed, for instance, in non-PatentLiterature 1.

Non-Patent Literature 1 describes carbazolyl dicyanobenzene (CDCB) as aluminescent material for TADF. Non-Patent Literature 1 describes thatCDCB includes carbazole as a donor and dicyanobenzene as an electronacceptor and emits light in a range from a blue color (473 nm) to anorange color (577 nm).

CITATION LIST Non-Patent Literature(s)

-   Non-Patent Literature 1: Hiroki Uoyama et al. NATURE. vol. 492, pp.    234-238, Dec. 13, 2012

SUMMARY OF THE INVENTION Problem(s) to be Solved by the Invention

In order to practically use an organic EL device, a compound that emitslight in a long wavelength region with use of the TADF mechanism hasbeen desired.

An object of the invention is to provide a compound that emits light ina long wavelength region. Another object of the invention is to providea material for an organic electroluminescence device containing theabove compound, an organic electroluminescence device containing theabove compound, and electronic equipment including the organicelectroluminescence device.

Means for Solving the Problem(s)

According to an aspect of the invention, a compound represented by aformula (1) below is provided.

In the formula (1), k is an integer of 0 or more, m is an integer of 1or more, and n is an integer of 2 or more. L is a substituted orunsubstituted aromatic hydrocarbon ring having 6 to 30 ring carbonatoms. CN is a cyano group. D₁ and D₂ are each independently representedby one of a formula (2), a formula (3) and formula (3x) below. D₁ and D₂may be the same or different. A plurality of D₁ may be the same ordifferent. A plurality of D₂ may be the same or different.

R₁ to R₈ of the formula (2), R₁₁ to R₁₈ of the formula (3), and R₁₁₁ toR₁₁₈ of the formula (3x) each independently represent a hydrogen atom, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkylsilyl group having 3to 30 carbon atoms, a substituted or unsubstituted arylsilyl grouphaving 6 to 60 ring carbon atoms, a substituted or unsubstituted alkoxygroup having 1 to 30 carbon atoms, a substituted or unsubstitutedaryloxy group having 6 to 30 ring carbon atoms, a substituted orunsubstituted alkylamino group having 2 to 30 carbon atoms, asubstituted or unsubstituted arylamino group having 6 to 60 ring carbonatoms, a substituted or unsubstituted alkylthio group having 1 to 30carbon atoms, or a substituted or unsubstituted arylthio group having 6to 30 ring carbon atoms.

In the formula (2), at least one of combinations of substituentsselected from R₁ to R₈ is mutually bonded to form a cyclic structure.

In the formula (3), at least one of combinations of substituentsselected from R₁₁ to R₁₈ is optionally mutually bonded to form a cyclicstructure.

In the formula (3x), at least one of combinations of substituentsselected from R₁₁₁ to R₁₁₈ is optionally mutually bonded to form acyclic structure.

In the formulae (3) and (3x): A, B and C each independently represent acyclic structure represented by one of a formula (31) and a formula (32)below, each of the cyclic structure A, cyclic structure B, and cyclicstructure C being fused with its adjacent cyclic structures at anypositions; p, px and py are each independently an integer of 1 to 4;when p is an integer of 2 or more, a plurality of cyclic structures Aare the same or different; when px is an integer of 2 or more, aplurality of cyclic structures B are the same or different; and when pyis an integer of 2 or more, a plurality of cyclic structures C are thesame or different.

In the formula (31), R₁₉ and R₂₀ each independently represent the sameas R₁ to R₈ and are optionally mutually bonded to form a cyclicstructure.

In the formula (32): X₁ represents CR₃₀R₃₁, NR₃₂, a sulfur atom, or anoxygen atom and R₃₀ to R₃₂ each independently represent the same as R₁to R₈ described above. At least one of combinations of substituentsselected from R₁₉, R₂₀ and R₃₀ to R₃₂ are optionally mutually bonded toform a cyclic structure.

A material for an organic electroluminescence device according toanother aspect of the invention contains the compound in the aboveaspect of the invention.

An organic electroluminescence device according to still another aspectof the invention includes: an anode; a cathode; and one or more organiclayers interposed between the anode and the cathode, at least one of theorganic layers contains the compound according to the above aspect ofthe invention.

Electronic equipment includes the organic electroluminescence deviceaccording to the above aspect of the invention.

A compound according to the aspect of the invention emits light in along wavelength region. In the above aspect, a material for an organicelectroluminescence device containing the above compound, an organicelectroluminescence device containing the above compound, and electronicequipment including the organic electroluminescence device can beprovided.

BRIEF DESCRIPTION OF DRAWING(S)

FIG. 1 schematically shows an exemplary arrangement of an organic ELdevice according to an exemplary embodiment.

FIG. 2 shows a relationship in energy level and energy transfer betweenthe host material and the dopant material in the emitting layer.

FIG. 3 schematically shows an exemplary arrangement of an organic ELdevice according to a modification.

DESCRIPTION OF EMBODIMENT(S)

Exemplary embodiment(s) will be described below.

First Exemplary Embodiment

Compound(s)

A compound in the first exemplary embodiment is represented by a formula(1) below.

In the formula (1), k is an integer of 0 or more, m is an integer of 1or more, and n is an integer of 2 or more. L is a substituted orunsubstituted aromatic hydrocarbon ring having 6 to 30 ring carbonatoms. CN is a cyano group.

D₁ and D₂ are each independently represented by one of a formula (2), aformula (3) and formula (3x) below. D₁ and D₂ may be mutually the sameor different. When m is 2 or more, a plurality of D₁ may be mutually thesame or different. When k is 2 or more, a plurality of D₂ may bemutually the same or different.

R₁ to R₈ of the formula (2), R₁₁ to R₁₈ of the formula (3), and R₁₁₁ toR₁₁₈ of the formula (3x) each independently represent a hydrogen atom, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkylsilyl group having 3to 30 carbon atoms, a substituted or unsubstituted arylsilyl grouphaving 6 to 60 ring carbon atoms, a substituted or unsubstituted alkoxygroup having 1 to 30 carbon atoms, a substituted or unsubstitutedaryloxy group having 6 to 30 ring carbon atoms, a substituted orunsubstituted alkylamino group having 2 to 30 carbon atoms, asubstituted or unsubstituted arylamino group having 6 to 60 ring carbonatoms, a substituted or unsubstituted alkylthio group having 1 to 30carbon atoms, or a substituted or unsubstituted arylthio group having 6to 30 ring carbon atoms.

In the formula (2), at least one of combinations of substituentsselected from R₁ to R₈ is mutually bonded to form a cyclic structure.Specifically, in the formula (2), substituents selected from R₁ to R₈that are respectively bonded to adjacent ones of the carbon atoms of thesix-membered rings to which R₁ to R₈ are respectively bonded form acyclic structure. Specifically, in the formula (2), at least one ofcombinations of substituents, namely, a combination of R₁ and R₂, acombination of R₂ and R₃, a combination of R₃ and R₄, a combination ofR₄ and R₅, a combination of R₅ and R₆, a combination of R₆ and R₇, and acombination of R₇ and R₈ is mutually bonded to form a cyclic structure.In the first exemplary embodiment, the cyclic structure formed bybonding the substituents is preferably a fused ring. When the cyclicstructure is formed in the formula (2), the formed structure ispreferably a fused six-membered cyclic structure.

In the formula (3), at least one of combinations of substituentsselected from R₁₁ to R₁₈ may be mutually bonded to form a cyclicstructure.

In the formula (3x), at least one of combinations of substituentsselected from R₁₁₁ to R₁₁₈ may be mutually bonded to form a cyclicstructure.

In the formulae (3) and (3x), A, B and C each independently represent acyclic structure represented by one of a formula (31) and a formula (32)below. Each of the cyclic structure A, cyclic structure B, and cyclicstructure C is fused with its adjacent cyclic structures at anypositions. p, px and py are each independently an integer of 1 to 4.When p is an integer of 2 or more, a plurality of cyclic structures Amay be the same or different. When px is an integer of 2 or more, aplurality of cyclic structures B may be the same or different. When pyis an integer of 2 or more, a plurality of cyclic structures C may bethe same or different.

In the formula (31), R₁₉ and R₂₀ each independently represent the sameas R₁ to R₈ described above and may be mutually bonded to form a cyclicstructure. R₁₉ and R₂₀ are respectively bonded to carbon atoms formingthe benzene ring of the formula (31).

In the formula (32), X₁ represents CR₃₀R₃₁, NR₃₂, a sulfur atom, or anoxygen atom and R₃₀ to R₃₂ each independently represent the same as R₁to R₈ described above. At least one of combinations of substituentsselected from R₁₉, R₂₀ and R₃₀ to R₃₂ may be mutually bonded to form acyclic structure.

In the first exemplary embodiment, D₁ and D₂ represented by one of theformula (2), the formula (3) and the formula (3x) is a compound havingan extended carbazol skeleton. Accordingly, in the compound in the firstexemplary embodiment, conjugation is extended, an energy gap is reduced,and an emission wavelength is closer to a long wavelength. Moreover,since the compound in the first exemplary embodiment has two or morecyano groups, the energy gap is reduced and the emission wavelength iscloser to a long wavelength. Here, it is not sufficient to simply extendthe conjugation. It is further required to extend the conjugation sothat ΔST is reduced. As for this point, a method of extending theconjugation by extending the carbazole skeleton is useful in a moleculardesign. Moreover, in a later-described exemplary embodiment, theemission wavelength can be further lengthened by further introducing adonating substituent or a conjugated substituent to a terminal of thecarbazole skeleton.

In the first exemplary embodiment, when L has a substituent, thesubstituent is preferably a halogen atom, a substituted or unsubstitutedaryl group having 6 to 30 ring carbon atoms, a substituted orunsubstituted heterocyclic group having 6 to 30 ring atoms, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkylsilyl group having 3 to 30 carbonatoms, or a substituted or unsubstituted arylsilyl group having 6 to 60ring carbon atoms. When L has a plurality of substituents, the pluralityof substituents may be the same or different.

In the first exemplary embodiment, L is preferably a substituted orunsubstituted aromatic hydrocarbon ring having 6 to 14 ring carbonatoms. Examples of the aromatic hydrocarbon ring having 6 to 14 ringcarbon atoms include benzene, naphthalene, fluorene and phenanthrene.The aromatic hydrocarbon ring having 6 to 10 ring carbon atoms is morepreferable.

In the first exemplary embodiment, in the formula (1), it is preferablethat D₁ or D₂ is bonded to a first one of the carbon atoms forming thearomatic hydrocarbon ring represented by L and CN is bonded to a secondone of the carbon atoms adjacent to the first one. For instance, in thecompound of the first exemplary embodiment, it is preferable that D isbonded to the first carbon atoms C₁ and a cyano group is bonded to thesecond carbon atoms C₂ adjacent to the first carbon atoms C₁ as shown ina partial structure represented by a formula (1a) below. D in theformula (1a) below represents D₁ or D₂ described above. In the formula(1a), a wavy line represents a bonding position with another structureor an atom.

Since D₁ or D₂ having a skeleton represented by the formula (2), (3) or(3x) and the cyano group are adjacently bonded to the aromatichydrocarbon ring represented by L, a value of ΔST of the compound can bereduced.

In the first exemplary embodiment, m is preferably an integer of 2 ormore. When 2 or more D₁ are bonded to the aromatic hydrocarbon ringrepresented by L, the plurality of D₁ may be the same or different inthe structure.

In the first exemplary embodiment, the compound is preferablyrepresented by a formula (40) below.

In the formula (40), k is an integer of 0 to 3, m is an integer of 1 to4, n is an integer of 2 to 5, q is an integer of 0 to 3, and k+m+n+q=6.

In the formula (40), R_(X) represents a hydrogen atom, a halogen atom, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 6 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkylsilyl group having 3to 30 carbon atoms, or a substituted or unsubstituted arylsilyl grouphaving 6 to 60 ring carbon atoms. A plurality of R_(X) may be the sameor different.

In the formula (40), D₁ and D₂ each independently represent the same asD₁ and D₂ of the formula (1). A plurality of D₁ may be mutually the sameor different. A plurality of D₂ may be mutually the same or different.

In the formula (40), R_(X), D₁, D₂ and CN are respectively bonded tocarbon atoms forming the benzene ring.

In the first exemplary embodiment, the compound is preferablyrepresented by a formula (40a) below.

In the formula (40a), k is an integer of 0 to 3, n is an integer of 2 to5, q is an integer of 0 to 3, and k+n+q=5.

In the formula (40a), R_(X) represents the same as R_(X) in the formula(40). A plurality of R_(X) may be the same or different.

In the formula (40a), D₁ and D₂ each independently represent the same asD₁ and D₂ in the formula (1). A plurality of D₂ may be the same ordifferent.

In the formula (40a), R_(X), D₂ and CN are respectively bonded to carbonatoms forming the benzene ring.

For instance, the compound represented by the formula (40a) has askeleton in which D₁ is bonded at a para-position to the cyano groupbonded to the benzene ring. The compound having such a skeleton ispreferable since having a higher fluorescence quantum yield.

In the first exemplary embodiment, the compound is also preferablyrepresented by a formula (40b) or a formula (40c) below.

In the formulae (40b) and (40c), k is an integer of 0 to 3, q is aninteger of 0 to 3, and k+q=3.

In the formulae (40b) and (40c), R_(X) represents the same as R_(X) inthe formula (40). A plurality of R_(X) may be the same or different.

In the formulae (40b) and (40c), D₁ and D₂ each independently representthe same as D₁ and D₂ in the formula (1). A plurality of D₂ may be thesame or different.

In the formulae (40b) and (40c), R_(X) and D₂ are respectively bonded tocarbon atoms forming the benzene ring.

In the first exemplary embodiment, the compound is also preferablyrepresented by a formula (40d) or a formula (40e) below.

In the formulae (40d) and (40e), kx is an integer of 0 to 2, qx is aninteger of 0 to 2, and kx+qx=2.

In the formulae (40d) and (40e), R_(X) represents the same as R_(X) inthe formula (40). A plurality of R_(X) may be the same or different.

In the formulae (40d) and (40e), D₁ and D₂ each independently representthe same as D₁ and D₂ in the formula (1). A plurality of D₂ may be thesame or different.

In the formulae (40d) and (40e), R_(X) and D₂ are respectively bonded tocarbon atoms forming the benzene ring.

In the first exemplary embodiment, the compound is also preferablyrepresented by a formula (40f) below.

In the formula (40f), kx is an integer of 0 to 2, qy is an integer of 0to 2, and kx+qy=2.

In the formula (40f), R_(X1) represents a halogen atom, a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms, a substitutedor unsubstituted heterocyclic group having 6 to 30 ring atoms, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkylsilyl group having 3 to 30 carbonatoms, or a substituted or unsubstituted arylsilyl group having 6 to 60ring carbon atoms. R_(X2) represents the same as R_(X) in the formula(40). R_(X1) and R_(X2) may be the same or different. A plurality ofR_(X2) may be the same or different.

In the formula (40f), D₁ and D₂ each independently represent the same asD₁ and D₂ in the formula (1). A plurality of D₂ may be the same ordifferent.

In the formula (40f), R_(X2) and D₂ are respectively bonded to carbonatoms forming the benzene ring.

For instance, in the compound represented by the formula (40e) and thecompound represented by the formula (40f), D₁ is bonded to the firstcarbon atom of the benzene ring and D₂ or R_(X1) is bonded to the secondcarbon atom adjacent to the first carbon atom as described in relationto the formula (1a). The compounds having such a skeleton are preferablesince exhibiting a shorter delayed fluorescence lifetime.

In the first exemplary embodiment, the compound is preferablyrepresented by a formula (40g) below.

In the formula (40g), k is an integer of 0 to 3, q is an integer of 0 to3, and k+q=3.

In the formula (40g), R_(X) each independently represents the same asR_(X) in the formula (40). A plurality of R_(X) may be the same ordifferent.

In the formula (40g), D₁ and D₂ each independently represent the same asD₁ and D₂ in the formula (1). A plurality of D₂ may be the same ordifferent.

In the formula (40g), R_(X) and D₂ are respectively bonded to carbonatoms forming the benzene ring.

For instance, the compound represented by the formula (40g) has askeleton in which the cyano groups are bonded to the benzene ring atpara-positions. The compound having such a skeleton is preferable sinceexhibiting a shorter fluorescence quantum yield.

A compound in the first exemplary embodiment is preferably representedby a formula (4) below.

In the formula (4), k is an integer of 0 to 3, m is an integer of 1 to4, n is an integer of 2 to 5, q is an integer of 0 to 3, and k+m+n+q=6.In the first exemplary embodiment, x is preferably an integer of 2 to 4and m is preferably an integer of 2 to 4.

In the formula (4), R₄₀ each independently represents a hydrogen atom, ahalogen atom, a substituted or unsubstituted aryl group having 6 to 30ring carbon atoms, a substituted or unsubstituted alkyl group having 1to 30 carbon atoms, a substituted or unsubstituted alkylsilyl grouphaving 3 to 30 carbon atoms, or a substituted or unsubstituted arylsilylgroup having 6 to 60 ring carbon atoms. A plurality of R₄₀ may be thesame or different.

In the formula (4), D₁ and D₂ each independently represent the same asD₁ and D₂ of the formula (1). A plurality of D₁ may be mutually the sameor different. A plurality of D₂ may be mutually the same or different.

In the formula (4), R₄₀, D₁, D₂ and CN are respectively bonded to carbonatoms forming the benzene ring.

In the first exemplary embodiment, the compound represented by theformula (4) is preferably represented by one of formulae (41) to (47)below.

In the formulae (41) to (43), D₁ and D₂ each independently represent thesame as D₁ and D₂ in the formula (1) and R₄₀ each independentlyrepresents the same as R₄₀ in the formula (4).

In the formulae (41) to (43), k is an integer of 0 to 3, m is an integerof 1 to 4, q is an integer of 0 to 3, and k+m+q=4.

In the formulae (44) to (46), k is an integer of 0 to 2, m is an integerof 1 to 3, q is an integer of 0 to 2, and k+m+q=3.

In the formula (47), k is 0 or 1, m is 1 or 2, and q is 0 or 1, andk+m+q=2.

In the first exemplary embodiment, in the formulae (41) to (46), it ispreferable that D₁ or D₂ is bonded to the carbon atom (second carbonatom) adjacent to the carbon atom (the first carbon atom) of the benzenering to which CN is bonded in the same manner as in the formula (47).The value of ΔST of the compound can be reduced when D₁ or D₂ and CN areadjacently bonded to the benzene ring.

In the first exemplary embodiment, m of the formulae (41) to (47) ispreferably 2. Moreover, it is more preferable that m is 2 and k is 0. Aplurality of D₁ may be mutually the same or different in the structure.

In the first exemplary embodiment, the compound is preferablyrepresented by a formula (4x) below.

In the formula (4x), k is an integer of 0 to 3, m is an integer of 1 to4, n is an integer of 2 to 5, q is an integer of 0 to 3, and k+m+n+q=6.

In the formula (4x), R₅₀ each independently represents a substituted orunsubstituted heterocyclic group having 6 to 30 ring atoms. A pluralityof R₅₀ may be the same or different.

In the formula (4x), D₁ and D₂ each independently represent the same asD₁ and D₂ of the formula (1). A plurality of D₁ may be mutually the sameor different. A plurality of D₂ may be mutually the same or different.

In the formula (4x), R₅₀, D₁, D₂ and CN are respectively bonded tocarbon atoms forming the benzene ring.

R₅₀ is preferably each independently a group selected from the groupconsisting of a substituted or unsubstituted 1-carbazolyl group, asubstituted or unsubstituted 2-carbazolyl group, a substituted orunsubstituted 3-carbazolyl group, a substituted or unsubstituted4-carbazolyl group, and a substituted or unsubstituted 9-carbazolylgroup.

In the first exemplary embodiment, the compound represented by theformula (4x) is preferably represented by one of formulae (51) to (57)below.

In the formulae (51) to (53), D₁ and D₂ each independently represent thesame as D₁ and D₂ in the formula (1) and R₅₀ each independentlyrepresents the same as R₅₀ in the formula (4x).

In the formulae (51) to (53), k is an integer of 0 to 3, m is an integerof 1 to 4, q is an integer of 0 to 3, and k+m+q=4.

In the formulae (54) to (56), k is an integer of 0 to 2, m is an integerof 1 to 3, q is an integer of 0 to 2, and k+m+q=3.

In the formula (57), k is 0 or 1, m is 1 or 2, and q is 0 or 1, andk+m+q=2.

In the first exemplary embodiment, in the formulae (51) to (56), it ispreferable that D₁ or D₂ is bonded to the carbon atom (second carbonatom) adjacent to the carbon atom (the first carbon atom) of the benzenering to which CN is bonded in the same manner as in the formula (57).The value of ΔST of the compound can be reduced when D₁ or D₂ and CN areadjacently bonded to the benzene ring.

In the first exemplary embodiment, m of the formulae (51) to (57) ispreferably 2. Moreover, it is more preferable that m is 2 and k is 0. Aplurality of D₁ may be mutually the same or different in the structure.It is more preferable that a first one of D₁ is bonded to the benzenering and a second one of D₁ is bonded to the benzene ring at apara-position or a meta-position relative to the first one of D₁.

A compound in the first exemplary embodiment is preferably representedby one of formulae (48) to (50) below.

In the formula (48), R₄₁ and R₄₂ each independently represent the sameas R₁ to R₈ described above.

In the formulae (48) to (50), D each independently represents the sameas D₁ or D₂ of the formula (1).

In the first exemplary embodiment, in the formula (2), it is preferablethat one or two of combinations of substituents selected from R₁ to R₈are mutually bonded to form a cyclic structure. Specifically, as D₁ orD₂ represented by the formula (2), it is preferable that one or two ofcombinations of substituents, namely, a combination of R₁ and R₂, acombination of R₂ and R₃, a combination of R₃ and R₄, a combination ofR₄ and R₅, a combination of R₅ and R₆, a combination of R₆ and R₇, and acombination of R₇ and R₈ are mutually bonded to form a cyclic structure.It is more preferable that at least one of the combination of R₂ and R₃,the combination of R₃ and R₄, the combination of R₅ and R₆, and thecombination of R₆ and R₇ is mutually bonded to form a cyclic structure.In this arrangement, since the cyclic structure is formed including atleast one of a carbon atom at a position 3 and a carbon atom at aposition 6 of the carbazole skeleton of the formula (2), it is inferredthat an active site of the carbazole skeleton is modified by this cyclicstructure, thereby improving the stability of the compound in the firstexemplary embodiment.

In the first exemplary embodiment, at least one of D₁ and D₂ representedby the formula (2) is preferably represented by one of formulae (21) to(26) below.

In the formulae (21) to (26), R₁ to R₈, R₂₁ and R₂₂ each independentlyrepresent the same as R₁ to R₈ described above, r and s are each 4, andR₂₁ and R₂₂ are each bonded to a carbon atom of a six-membered ring. Aplurality of R₂₁ may be mutually the same or different. A plurality ofR₂₂ may be mutually the same or different.

In the formulae (21) to (26), at least one of combinations ofsubstituents selected from R₁ to R₈, R₂₁ and R₂₂ may be mutually bondedto form a cyclic structure.

In the first exemplary embodiment, at least one of D₁ and D₂ representedby the formula (2) is preferably represented by one of formulae (201) to(203) below.

In the formulae (201) to (203), R₇, R₈, R₂₂ to R₂₅ each independentlyrepresent the same as R₁ to R₈ described above. X₂ represents CR₂₆R₂₇,NR₂₈, a sulfur atom, or an oxygen atom. R₂₆ to R₂₈ each independentlyrepresent the same as R₁ to R₈ described above. s is 4. t is an integerof 1 to 4. u and v are each 4. A plurality of R_(n) may be mutually thesame or different. A plurality of R₂₃ may be mutually the same ordifferent. A plurality of R₂₄ may be mutually the same or different. Aplurality of R₂₅ may be mutually the same or different.

It is inferred that, since a particular substituent is further bonded tothe carbazole skeleton fused with a ring as shown in the formulae (201)to (203), an emission wavelength of the compound in the first exemplaryembodiment is shifted toward a longer wavelength as compared with anarrangement in which the substituent is not bonded.

In the formulae (201) to (203), at least one of combinations ofsubstituents selected from R₇, R₈, and R₂₂ to R₂₅ may be mutually bondedto form a cyclic structure.

In the formulae (201) to (203), t is preferably 1.

A compound represented by a formula (201a) is preferable among thecompound represented by the formula (201). A compound represented by aformula (202a) is preferable among the compound represented by theformula (202). A compound represented by a formula (203a) is preferableamong the compound represented by the formula (203).

In the formulae (201a), (202a) and (203a); R₇, R₈, and R₂₂ to R₂₅ eachindependently represent the same as R₁ to R₈ described above; X₂represents CR₂₆R₂₇, NR₂₈, a sulfur atom, or an oxygen atom; R₂₆ to R₂₈each independently represent the same as R₁ to R₈ described above; s is4; w is 3; and u and v are each 4. A plurality of R₂₂ may be mutuallythe same or different. A plurality of R₂₃ may be mutually the same ordifferent. A plurality of R₂₄ may be mutually the same or different. Aplurality of R₂₅ may be mutually the same or different.

When the compound in the first exemplary embodiment includes at leastone of the structures represented by the formulae (201a), (202a) and(203a), at least one of the carbon atoms at the position 3 and thecarbon atom at the position 6 of the carbazole skeleton is substitutedby a predetermined substituent. Accordingly, it is inferred that, sincethe carbon atoms at the positions 3 and 6 of the carbazole skeleton aremodified by the fused ring or are substituted by the substituent, thestability of the compound in the first exemplary embodiment is furtherimproved. Consequently, when the compound in the first exemplaryembodiment is used in an organic electroluminescence device, thelifetime of the organic electroluminescence device can be prolonged.

In the first exemplary embodiment, it is preferable that p is 2, inother words, two cyclic structures A are present in the formula (3). Inthis arrangement, the formula (3) is represented by a formula (3a)below.

In the formula (3a), R₁₁ to R₁₈ represent the same as R₁₁ to R₁₈ of theformula (3).

In the formula (3a), a cyclic structure A1 and a cyclic structure A2each independently represent the same as the cyclic structure Arepresented by the formula (31) or (32).

In the formula (3a), it is preferable that the cyclic structure A1 isthe cyclic structure represented by the formula (31) and the cyclicstructure A2 is the cyclic structure represented by the formula (32).

In the first exemplary embodiment, at least one of D₁ and D₂ representedby the formula (3) is preferably represented by one of formulae (33) to(38) below.

In the formulae (33) to (38), R₁₁ to R₁₈ each independently representthe same as R₁₁ to R₁₈ in the formula (3), and R₁₉ and R₂₀ eachindependently represent the same as R₁₉ and R₂₀ in the formula (31), andX₁ represents the same as X₁ in the formula (32).

In the formulae (33) to (38), at least one of combinations ofsubstituents selected from R₁₁ to R₂₀ may be mutually bonded to form acyclic structure.

In the first exemplary embodiment, at least one of D₁ and D₂ representedby the formula (3) is preferably represented by one of the formulae (33)to (36).

Since the cyclic structure represented by the formula (31) is fused tothe cyclic structure represented by the formula (32) as shown in theformulae (33) to (36), the cyclic structure includes at least one of thecarbon atoms at the positions 3 and 6 of the carbazole skeleton.Accordingly, it is inferred that the active site of the carbazoleskeleton is modified by the cyclic structure to improve the stability ofthe compound in the first exemplary embodiment.

In the first exemplary embodiment, at least one of D₁ and D₂ representedby the formula (3) is also preferably the structure represented by oneof the formulae (33) and (34), in which X₁ is CR₃₀R₃₁. In thisarrangement, the formula (33) is represented by a formula (33a) belowand the formula (34) is represented by a formula (34a) below.

In the formulae (33a) and (34a), R₁₁ to R₁₈ each independently representthe same as R₁₁ to R₁₈ in the formula (3) and R₁ and R₂ eachindependently represent the same as R₃₀ and R₃₁ in the formula (32).

In the formulae (33a) and (34a), at least one of combinations ofsubstituents selected from R₁₁ to R₁₈, R₃₀ and R₃₁ may be mutuallybonded to form a cyclic structure.

In the first exemplary embodiment, R₃₀ and R₂₀ in the formula (33a) arepreferably mutually bonded to form a cyclic structure. Moreover, in theformula (34a), R₃₀ and R₁₉ are preferably mutually bonded to form acyclic structure.

In the first exemplary embodiment, at least one of D₁ and D₂ representedby the formula (3) is preferably represented by one of formulae (27) and(28) below.

In the formulae (27) and (28), R₁, R₄ to R₈, R₂₁ and R₂₂ eachindependently represent the same as R₁ to R₈ described above, r and sare each 4, and R₂₁ and R₂₂ are each bonded to a carbon atom of thesix-membered ring. A plurality of R₂₁ may be mutually the same ordifferent. A plurality of R_(n) may be mutually the same or different.

In the formulae (27) and (28), at least one of combinations ofsubstituents selected from R₁, R₄ to R₈, R₂₁ and R₂₂ may be mutuallybonded to form a cyclic structure. In this arrangement, since the cyclicstructure is formed including at least one of the carbon atom at theposition 3 and the carbon atom at the position 6 of the carbazoleskeleton as described above, it is inferred that the stability of thecompounds represented by the formulae (27) and (28) is improved.Consequently, also when the compounds represented by the formulae (27)and (28) are used in an organic electroluminescence device, a lifetimeof the organic electroluminescence device can be prolonged.

In the first exemplary embodiment, it is also preferable that D₁ and D₂are each independently represented by a formula (5) below.

In the formula (5), Xa represents an oxygen atom, a sulfur atom, NR¹⁰⁰or CR¹⁰³R¹⁰⁴.

Xb, Xc, Xd and Xe each independently represent a single bond, an oxygenatom, a sulfur atom, NR¹⁰⁰, CR¹⁰³R¹⁰⁴ or a nitrogen atom to be bonded toL of the formula (1).

At least one of Xa, Xb, Xc, Xd and Xe is NR¹. At least one of Xa, Xb,Xc, Xd and Xe is a nitrogen atom to be bonded to L of the formula (1).Xb and Xc are not simultaneously single bonds. Xd and Xe are notsimultaneously single bonds.

R¹⁰⁰ is selected from the group consisting of a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 30 ring carbonatoms, a substituted or unsubstituted aromatic hydrocarbon group having6 to 30 ring carbon atoms, a substituted or unsubstituted heterocyclicgroup having 5 to 30 ring atoms, and a group represented by -L¹-R¹⁰².

When a plurality of R¹⁰⁰ are present, the plurality of R¹⁰⁰ may bemutually the same or different.

L¹ represents a single bond or a linking group. When L¹ is a linkinggroup, the linking group is selected from the group consisting of asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms and a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms. When a plurality of L¹ are present, theplurality of L¹ may be mutually the same or different.

R¹⁰² to R¹⁰⁴ are each selected from the group consisting of a hydrogenatom, a substituted or unsubstituted alkyl group having 1 to 30 carbonatoms, a substituted or unsubstituted cycloalkyl group having 3 to 30ring carbon atoms, a substituted or unsubstituted aromatic hydrocarbongroup having 6 to 30 ring carbon atoms, and a substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms.

When a plurality of R¹⁰² are present, the plurality of R¹⁰² may bemutually the same or different.

When a plurality of R¹⁰³ are present, the plurality of R¹⁰³ may bemutually the same or different.

When a plurality of R¹⁰⁴ are present, the plurality of R¹⁰⁴ may bemutually the same or different.

Z¹, Z², Z³ and Z⁴ each independently represent a cyclic structureselected from the group consisting of a substituted or unsubstitutedaromatic hydrocarbon ring having 6 to 30 ring carbon atoms, and asubstituted or unsubstituted heterocyclic ring having 5 to 30 ringatoms.

It should be noted that Xe does not represent an element symbol of xenonin the present specification.

In the formula (5), Xa and a single bond connecting Z¹ and Z² arerespectively bonded to adjacent atoms of the cyclic structurerepresented by Z¹ and respectively bonded to adjacent atoms of thecyclic structure represented by Z². Xb and Xc are respectively bonded toadjacent atoms of the cyclic structure represented by Z² andrespectively bonded to adjacent atoms of the cyclic structurerepresented by Z³. Xd and Xe are respectively bonded to adjacent atomsof the cyclic structure represented by Z³ and respectively bonded toadjacent atoms of the cyclic structure represented by Z⁴.

When Z¹ is, for instance, a benzene ring in the formula (5), a bondingpattern of Z¹, Xa and a single bond is represented by a formula (5-1)below in which a wavy part represents a bonding position to Z².

When both of Z¹ and Z² are, for instance, benzene rings in the formula(5), a bonding pattern of Z¹, Xa, a single bond and Z² is represented byone of formulae (5-2), (5-3) and (5-4) below in which a wavy partrepresents a bonding position to Xb and Xc.

In the first exemplary embodiment, Z¹, Z², Z³ and Z⁴ are preferably eachindependently a substituted or unsubstituted aromatic hydrocarbon ringhaving 6 to 30 ring carbon atoms, more preferably a substituted orunsubstituted aromatic hydrocarbon ring having 6 to 20 ring carbonatoms, further preferably an aromatic hydrocarbon ring selected from thegroup consisting of a benzene ring, naphthalene ring, phenanthrene ring,and triphenylenylene ring, particularly preferably a benzene ring.

In the first exemplary embodiment, it is preferable that one of Xb andXc is a single bond and one of Xd and Xe is a single bond.

When one of Xb and Xc is a single bond and one of Xd and Xe is a singlebond, D₁ and D₂ represented by the formula (5) is represented by one offormulae (5A) to (5D) below.

In D₁ and D₂ represented by the formula (5A) or (5B), it is preferablethat Xa is NR¹⁰⁰ and Xd is a nitrogen atom to be bonded to L in theformula (1). In this arrangement, Xb and Xc are preferably an oxygenatom or a sulfur atom, more preferably an oxygen atom.

In D₁ and D₂ represented by the formula (5C) or (5D), it is preferablethat Xa is NR¹⁰⁰ and Xe is a nitrogen atom to be bonded to L in theformula (1). In this arrangement, Xb and Xc are preferably an oxygenatom or a sulfur atom, more preferably an oxygen atom.

An organic compound for expressing thermally activated delayedfluorescence is exemplified by a compound in which a donor moiety (amoiety having electron donating performance) is bonded to an acceptormoiety (a moiety having electron accepting performance) in a molecule.When the number of a nitrogen atom included in the skeleton representedby the formula (5) is increased, the electron donating performance ofthe donor moiety of a first compound is enhanced, thereby providing asuitable balance between the electron donating performance of the donormoiety and the electron accepting performance of the acceptor moiety inthe first compound. Consequently, the first compound exhibits suitablecharacteristics as a material for exhibiting delayed fluorescence.

In the first exemplary embodiment, at least one of R¹⁰⁰ is preferably agroup represented by -L¹-R¹⁰².

In the first exemplary embodiment, px and py of the formula (3x) arepreferably the same integer, more preferably 2. In this arrangement, theformula (3x) is represented by a formula (3y) below.

In the formula (3y), R₁₁₁ to R₁₁₈ each independently represent the sameas R₁₁₁ to R₁₁₈ described in the formula (3x).

The cyclic structure B1 and the cyclic structure B2 each independentlyrepresent the same as the cyclic structure B. The cyclic structure C1and the cyclic structure C2 each independently represent the same as thecyclic structure C.

In the formula (3y), it is preferable that the cyclic structure B1 andthe cyclic structure C1 are each independently the cyclic structurerepresented by the formula (31) and the cyclic structure B2 and thecyclic structure C2 are each independently the cyclic structurerepresented by the formula (32).

In the first exemplary embodiment, it is also preferable that D₁ and D₂are each independently represented by a formula (10) below.

D₁ and D₂ represented by the formula (10) below each have a ring in abonding pattern allowing a high triplet energy to be maintained.Accordingly, D₁ and D₂ represented by the formula (10) below arepreferable since D₁ and D₂ can effectively confine a high emissionenergy in a wavelength region from blue to green.

In the formula (10), Xf represents an oxygen atom, a sulfur atom, NR¹⁰⁰or CR¹⁰³R¹⁰⁴.

R¹⁰⁰ is selected from the group consisting of a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 30 ring carbonatoms, a substituted or unsubstituted aromatic hydrocarbon group having6 to 30 ring carbon atoms, a substituted or unsubstituted heterocyclicgroup having 5 to 30 ring atoms, and a group represented by -L¹-R¹⁰².

L¹ represents a single bond or a linking group. When L¹ is a linkinggroup, the linking group is selected from the group consisting of asubstituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms and a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms. When a plurality of L¹ are present, theplurality of L¹ may be mutually the same or different.

Y₁₁, Y₁₂, Y₁₃, Y₁₄, Y₁₅, Y₁₆, Y₁₇, Y₁₈, Y₁₉, Y₂₀, Y₂₁ and Y₂₂ eachindependently represent a nitrogen atom or CR¹⁰⁵.

R¹⁰² to R¹⁰⁵ are each independently selected from the group consistingof a hydrogen atom, a substituted or unsubstituted alkyl group having 1to 30 carbon atoms, a substituted or unsubstituted cycloalkyl grouphaving 3 to 30 ring carbon atoms, a substituted or unsubstitutedaromatic hydrocarbon group having 6 to 30 ring carbon atoms, and asubstituted or unsubstituted heterocyclic group having 5 to 30 ringatoms.

When a plurality of R¹⁰² are present, the plurality of R¹⁰² may bemutually the same or different.

When a plurality of R¹⁰⁵ are present, the plurality of R¹⁰⁵ may bemutually the same or different. When at least two of the plurality ofR¹⁰⁵ are substituents, R¹⁰⁵ of the substituents may be mutually bondedto form a cyclic structure.

A wavy part in the formula (10) shows a bonding position to L in theformula (1) and the like.

In the first exemplary embodiment, R¹⁰² is preferably each independentlya substituent selected from the group consisting of a substituted orunsubstituted aromatic hydrocarbon group having 6 to 30 ring carbonatoms and a substituted or unsubstituted heterocyclic group having 5 to30 ring atoms.

In the first exemplary embodiment, R¹⁰² is preferably each independentlya substituted or unsubstituted aromatic hydrocarbon group having 6 to 30ring carbon atoms, more preferably a substituted or unsubstitutedaromatic hydrocarbon group having 6 to 20 ring carbon atoms, furtherpreferably an aromatic hydrocarbon group selected from the groupconsisting of a phenyl group, biphenyl group, terphenyl group, naphthylgroup, phenanthryl group and triphenylenyl group.

In the first exemplary embodiment, Y₁₁, Y₁₂, Y₁₃, Y₁₄, Y₁₅, Y₁₆, Y₁₇,Y₁₈, Y₁₉, Y₂₀, Y₂₁ and Y₂₂ are preferably CR¹⁰⁵, in which R¹⁰⁵ is morepreferably a hydrogen atom. In this arrangement, for instance, theformula (10) is represented by a formula (10B) below.

In the formula (10B), Xf, L¹ and R¹⁰² each independently represent thesame as Xf, L¹ and R¹⁰² in the formula (10). A wavy part in the formula(10B) shows a bonding position to L in the formula (1) and the like.

In the formulae (10) and (10B), Xf is preferably an oxygen atom or asulfur atom, more preferably an oxygen atom.

In the first exemplary embodiment, when m is 2 or more, D₁ and D₂ arepreferably different from each other. When a plurality of D₁ arepresent, the plurality of D₁ may be mutually the same or different. Whena plurality of D₂ are present, the plurality of D₂ may be mutually thesame or different. When a plurality of D₁ and a plurality of D₂ arepresent, the plurality of D₁ and the plurality of D₂ may be mutually thesame or different.

The compound in the first exemplary embodiment may have: the structuresrepresented by the formulae (2) and (3); the structures represented bythe formulae (2) and (3x); the structures represented by the formulae(3) and (3x); a plurality of structures represented by the formula (2)that are mutually different in details; a plurality of structuresrepresented by the formula (3) that are mutually different in details;or a plurality of structures represented by the formula (3x) that aremutually different in details.

In the first exemplary embodiment, at least one of R₃ and R₆ ispreferably substituted by a substituent. In the first exemplaryembodiment, at least one of R₁₃ and R₁₆ is preferably substituted by asubstituent.

In the first exemplary embodiment, it is preferable that R₁ to R₈, R₁₁to R₁₈ and R₁₁₁ to R₁₁₈ are each independently a hydrogen atom, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkylsilyl group having 3to 30 carbon atoms, a substituted or unsubstituted arylsilyl grouphaving 6 to 60 ring carbon atoms, or a substituted or unsubstitutedarylamino group having 6 to 60 ring carbon atoms.

In the first exemplary embodiment, it is more preferable that R₁ to R₈,R₁₁ to R₁₈ and R₁₁₁ to R₁₁₈ are each independently a hydrogen atom, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 30ring atoms, a substituted or unsubstituted arylamino group having 6 to40 ring carbon atoms, or a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms.

In the first exemplary embodiment, it is further preferable that R₁ toR₈, R₁₁ to R₁₈ and R₁₁₁ to R₁₁₈ are each independently a hydrogen atom,a substituted or unsubstituted aryl group having 6 to 12 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 5 to 14ring atoms, or a substituted or unsubstituted alkyl group having 1 to 6carbon atoms.

In the first exemplary embodiment, it is preferable that R_(X) is eachindependently a hydrogen atom, a substituted or unsubstitutedheterocyclic group having 6 to 30 ring atoms, a substituted orunsubstituted alkyl group having 1 to 30 carbon atoms, or a substitutedor unsubstituted alkylsilyl group having 3 to 30 carbon atoms.

In the first exemplary embodiment, it is preferable that R_(X) is eachindependently a hydrogen atom, a substituted or unsubstitutedheterocyclic group having 6 to 14 ring atoms, a substituted orunsubstituted alkyl group having 1 to 6 carbon atoms, or a substitutedor unsubstituted alkylsilyl group having 3 to 18 carbon atoms.

In the first exemplary embodiment, carbon atoms forming a ring (alsoreferred to as “ring carbon atoms”) indicates the number of carbon atomsin atoms forming a ring of a compound in which the atoms are bonded toeach other to form a cyclic structure (e.g., monocyclic compound, fusedcyclic compound, cross-linking compound, carbon ring compound, andheterocyclic compound). When the ring is substituted by a substituent,the “ring carbon atoms” do not include carbon(s) contained in thesubstituent. Unless specifically described, the same applies to the“ring carbon atoms” described later. For instance, a benzene ring has 6ring carbon atoms, a naphthalene ring has 10 ring carbon atoms, apyridinyl group has 5 ring carbon atoms, and a furanyl group has 4 ringcarbon atoms. When the benzene ring and/or the naphthalene ring issubstituted by, for instance, an alkyl group, the number of carbon atomsof the alkyl group is not included in the number of the ring carbonatoms. When a fluorene ring is substituted by, for instance, a fluorenering (e.g., a spirofluorene ring), the number of carbon atoms of thefluorene ring as a substituent is not counted in the number of the ringcarbon atoms for the fluorene ring.

In the first exemplary embodiment, atoms forming a ring (also referredto as “ring atoms”) indicates the number of atoms forming a ring of acompound (e.g., monocyclic compound, fused cyclic compound,cross-linking compound, carbon ring compound, and heterocyclic compound)in which the atoms are bonded to each other to form a cyclic structure(e.g., monocyclic ring, fused ring, and ring system). Atom(s) notforming the ring (e.g., a hydrogen atom for terminating the atomsforming the ring) and atoms included in a substituent substituting thering are not counted in the number of the ring atoms. Unlessspecifically described, the same applies to the “ring atoms” describedlater. For instance, a pyridine ring has 6 ring atoms, a quinazolinering has 10 ring atoms, and a furan ring has 5 ring atoms. Hydrogenatoms and atoms forming the substituents respectively bonded to carbonatoms of the pyridine ring or the quinazoline ring are not counted inthe number of the ring atoms. When a fluorene ring is substituted by,for instance, a fluorene ring (e.g., a spirofluorene ring), the numberof atoms of the fluorene ring as a substituent is not included in thenumber of the ring atoms for the fluorene ring.

Next, each of substituents described in the above formulae will bedescribed.

In the first exemplary embodiment, examples of the aryl group(occasionally referred to as an aromatic hydrocarbon group) having 6 to30 ring carbon atoms include a phenyl group, biphenyl group, terphenylgroup, naphthyl group, anthryl group, phenanthryl group, fluorenylgroup, pyrenyl group, chrysenyl group, fluoranthenyl group,benzo[a]anthryl group, benzo[c]phenanthryl group, triphenylenyl group,benzo[k]fluoranthenyl group, benzo[g]chrysenyl group,benzo[b]triphenylenyl group, picenyl group, and perylenyl group.

The aryl group in the exemplary embodiment preferably has 6 to 20 ringcarbon atoms, more preferably 6 to 12 ring carbon atoms. Among the abovearyl group, a phenyl group, biphenyl group, naphthyl group, phenanthrylgroup, terphenyl group, and fluorenyl group are particularly preferable.A carbon atom at a position 9 of each of 1-fluorenyl group, 2-fluorenylgroup, 3-fluorenyl group and 4-fluorenyl group is preferably substitutedby a substituted or unsubstituted alkyl group having 1 to 30 carbonatoms or a substituted or unsubstituted aryl group having 6 to 18 ringcarbon atoms later described in the exemplary embodiment.

In the first exemplary embodiment, the heterocyclic group having 5 to 30ring atoms (occasionally referred to as a heteroaryl group,heteroaromatic cyclic group or an aromatic heterocyclic group) includes,as a hetero atom, preferably at least one atom selected from the groupconsisting of nitrogen, sulfur, oxygen, silicon, selenium and germanium,more preferably at least one atom selected from the group consisting ofnitrogen, sulfur and oxygen.

Examples of the heterocyclic group having 5 to 30 ring atoms in theexemplary embodiment include a pyridyl group, pyrimidinyl group,pyrazinyl group, pyridazynyl group, triazinyl group, quinolyl group,isoquinolinyl group, naphthyridinyl group, phthalazinyl group,quinoxalinyl group, quinazolinyl group, phenanthridinyl group, acridinylgroup, phenanthrolinyl group, pyrrolyl group, imidazolyl group,pyrazolyl group, triazolyl group, tetrazolyl group, indolyl group,benzimidazolyl group, indazolyl group, imidazopyridinyl group,benzotriazolyl group, carbazolyl group, furyl group, thienyl group,oxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group,oxadiazolyl group, thiadiazole group, benzofuranyl group,benzothiophenyl group, benzoxazolyl group, benzothiazolyl group,benzisoxazolyl group, benzisothiazolyl group, benzoxadiazolyl group,benzothiadiazolyl group, dibenzofuranyl group, dibenzothiophenyl group,piperidinyl group, pyrrolidinyl group, piperazinyl group, morpholylgroup, phenazinyl group, phenothiazinyl group, and phenoxazinyl group.

The heterocyclic group in the exemplary embodiment preferably has 5 to20 ring atoms, more preferably 5 to 14 ring atoms. Among the aboveheterocyclic group, a 1-dibenzofuranyl group, 2-dibenzofuranyl group,3-dibenzofuranyl group, 4-dibenzofuranyl group, 1-dibenzothiophenylgroup, 2-dibenzothiophenyl group, 3-dibenzothiophenyl group,4-dibenzothiophenyl group, 1-carbazolyl group, 2-carbazolyl group,3-carbazolyl group, 4-carbazolyl group, and 9-carbazolyl group areparticularly preferable. A nitrogen atom at a position 9 of each of1-carbazolyl group, 2-carbazolyl group, 3-carbazolyl group and4-carbazolyl group is preferably substituted by a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms or asubstituted or unsubstituted heterocyclic group having 5 to 30 ringatoms in the exemplary embodiment.

The alkyl group having 1 to 30 carbon atoms in the exemplary embodimentis preferably linear, branched or cyclic. Examples of the linear orbranched alkyl group include: a methyl group, ethyl group, n-propylgroup, isopropyl group, n-butyl group, s-butyl group, isobutyl group,t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octylgroup, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group,n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecylgroup, n-heptadecyl group, n-octadecyl group, neopentyl group, amylgroup, isoamyl group, 1-methylpentyl group, 2-methylpentyl group,1-pentylhexyl group, 1-butylpentyl group, 1-heptyloctyl group, and3-methylpentyl group.

The linear or branched alkyl group in the exemplary embodimentpreferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbonatoms. Among the linear or branched alkyl group, a methyl group, ethylgroup, propyl group, isopropyl group, n-butyl group, s-butyl group,isobutyl group, t-butyl group, n-pentyl group, n-hexyl group, amylgroup, isoamyl group, and neopentyl group are particularly preferable.

Examples of the cycloalkyl group in the exemplary embodiment include acyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexylgroup, 4-methylcyclohexyl group, adamantyl group and norbornyl group.The cycloalkyl group preferably has 3 to 10 ring carbon atoms, morepreferably 5 to 8 ring carbon atoms. Among the above cycloalkyl group, acyclopentyl group and a cyclohexyl group are particularly preferable.

A halogenated alkyl group provided by substituting the alkyl group witha halogen atom is exemplified by a halogenated alkyl group provided bysubstituting the alkyl group having 1 to 30 carbon atoms with one ormore halogen groups. Specific examples of the halogenated alkyl groupincludes a fluoromethyl group, difluoromethyl group, trifluoromethylgroup, fluoroethyl group, trifluoromethylmethyl group, trifluoroethylgroup, and pentafluoroethyl group.

The alkylsilyl group having 3 to 30 carbon atoms in the exemplaryembodiment is exemplified by a trialkylsilyl group having the abovealkyl group having 1 to 30 carbon atoms. Specific examples of thetrialkylsilyl group include a trimethylsilyl group, triethylsilyl group,tri-n-butylsilyl group, tri-n-octylsilyl group, triisobutylsilyl group,dimethylethylsilyl group, dimethylisopropylsilyl group,dimethyl-n-propylsilyl group, dimethyl-n-butylsilyl group,dimethyl-t-butylsilyl group, diethylisopropylsilyl group,vinyldimethylsilyl group, propyldimethylsilyl group andtriisopropylsilyl group. Three alkyl groups in the trialkylsilyl groupmay be mutually the same or different.

Examples of the arylsilyl group having 6 to 60 ring carbon atoms in theexemplary embodiment include a dialkylarylsilyl group, alkyldiarylsilylgroup and triarylsilyl group.

The dialkylarylsilyl group is exemplified by a dialkylarylsilyl grouphaving two of the examples of the alkyl group having 1 to 30 carbonatoms and one of the aryl group having 6 to 30 ring carbon atoms. Thedialkylarylsilyl group preferably has 8 to 30 carbon atoms.

The alkyldiarylsilyl group is exemplified by an alkyldiarylsilyl grouphaving one of the examples of the alkyl group having 1 to 30 carbonatoms and two of the aryl group having 6 to 30 ring carbon atoms. Thedialkylarylsilyl group preferably has 13 to 30 carbon atoms.

The triarylsilyl group is exemplified by a triarylsilyl group havingthree of the aryl group having 6 to 30 ring carbon atoms. Thetriarylsilyl group preferably has 18 to 30 carbon atoms.

The alkoxy group having 1 to 30 carbon atoms in the exemplary embodimentis represented by —OZ₁. —OZ₁ is exemplified by the above alkyl grouphaving 1 to 30 carbon atoms. Examples of the alkoxy group include amethoxy group, ethoxy group, propoxy group, butoxy group, pentyloxygroup and hexyloxy group.

A halogenated alkoxy group provided by substituting the alkoxy groupwith a halogen atom is exemplified by a halogenated alkoxy groupprovided by substituting the alkoxy group having 1 to 30 carbon atomswith one or more halogen groups.

The aryloxy group having 6 to 30 ring carbon atoms in the exemplaryembodiment is represented by —OZ₂. Z₂ is exemplified by the above arylgroup having 6 to 30 ring carbon atoms. The aryloxy group is exemplifiedby a phenoxy group.

The alkylamino group having 2 to 30 carbon atoms is represented by—NHR_(V) or —N(R_(V))₂. R_(V) is exemplified by the alkyl group having 1to 30 carbon atoms.

The arylamino group having 6 to 60 ring carbon atoms is represented by—NHR_(W) or —N(R_(W))₂. R_(W) is exemplified by the above aryl grouphaving 6 to 30 ring carbon atoms.

The alkylthio group having 1 to 30 carbon atoms is represented by—SR_(V). R_(V) is exemplified by the alkyl group having 1 to 30 carbonatoms.

The arylthio group having 6 to 30 ring carbon atoms is represented by—SR_(W). R_(W) is exemplified by the above aryl group having 6 to 30ring carbon atoms.

In the invention, “carbon atoms forming a ring (ring carbon atoms)” meancarbon atoms forming a saturated ring, unsaturated ring, or aromaticring. “Atoms forming a ring (ring atoms)” mean carbon atoms and heteroatoms forming a hetero ring including a saturated ring, unsaturatedring, or aromatic ring.

In the invention, a “hydrogen atom” means isotopes having differentneutron numbers and specifically encompasses protium, deuterium andtritium.

Examples of the substituents in the first exemplary embodiment(“substituted or unsubstituted”) and the substituent in the cyclicstructures A, A1, A2, B, B1, B2, C, C1, C2, Z¹ to Z⁴ and the like are analkenyl group, alkynyl group, aralkyl group, halogen atom, cyano group,hydroxyl group, nitro group and carboxy group, in addition to theabove-described aryl group, heterocyclic group, alkyl group (linear orbranched alkyl group, cycloalkyl group and haloalkyl group), alkylsilylgroup, arylsilyl group, alkoxy group, aryloxy group, alkylamino group,arylamino group, alkylthio group, and arylthio group.

In the above-described substituents, the aryl group, heterocyclic group,alkyl group, halogen atom, alkylsilyl group, arylsilyl group and cyanogroup are preferable. The preferable ones of the specific examples ofeach substituent are further preferable.

The alkenyl group is preferably an alkenyl group having 2 to 30 carbonatoms, which may be linear, branched or cyclic. Examples of the alkenylgroup include a vinyl group, propenyl group, butenyl group, oleyl group,eicosapentaenyl group, docosahexaenyl group, styryl group,2,2-diphenylvinyl group, 1,2,2-triphenylvinyl group, 2-phenyl-2-propenylgroup, cyclopentadienyl group, cyclopentenyl group, cyclohexenyl group,and cyclohexadienyl group.

The alkynyl group is preferably an alkynyl group having 2 to 30 carbonatoms, which may be linear, branched or cyclic. Examples of the alkynylgroup include ethynyl, propynyl, and 2-phenylethynyl.

The aralkyl group is preferably an aralkyl group having 6 to 30 ringcarbon atoms and is represented by —Z₃—Z₄. Z₃ is exemplified by analkylene group derived from the above alkyl group having 1 to 30 carbonatoms. Z₄ is exemplified by the above aryl group having 6 to 30 ringcarbon atoms. This aralkyl group is preferably an aralkyl group having 7to 30 carbon atoms, in which an aryl moiety has 6 to 30 carbon atoms,preferably 6 to 20 carbon atoms, more preferably 6 to 12 carbon atomsand an alkyl moiety has 1 to 30 carbon atoms, preferably 1 to 20 carbonatoms, more preferably 1 to 10 carbon atoms, further preferably 1 to 6carbon atoms. Examples of the aralkyl group include a benzyl group,2-phenylpropane-2-yl group, 1-phenylethyl group, 2-phenylethyl group,1-phenylisopropyl group, 2-phenylisopropyl group, phenyl-t-butyl group,α-naphthylmethyl group, 1-α-naphthylethyl group, 2-α-naphthylethylgroup, 1-α-naphthylisopropyl group, 2-α-naphthylisopropyl group,β-naphthylmethyl group, 1-β-naphthylethyl group, 2-β-naphthylethylgroup, 1-β-naphthylisopropyl group, and 2-β-naphthylisopropyl group.

Examples of the halogen atom are fluorine, chlorine, bromine and iodine,among which a fluorine atom is preferable.

“Unsubstituted” in “substituted or unsubstituted” herein means that agroup is not substituted by the above-described substituents but bondedwith a hydrogen atom.

Examples of a substituent in “substituted or unsubstituted” hereininclude the above-described substituents. The substituent may be furthersubstituted by the above-described substituents. The substituent in“substituted or unsubstituted” herein may be provided by a plurality ofsubstituents. The plurality of substituents may be mutually bonded toform a ring.

In the exemplary embodiment, “XX to YY carbon atoms” in the descriptionof “substituted or unsubstituted ZZ group having XX to YY carbon atoms”represent carbon atoms of an unsubstituted ZZ group and do not includecarbon atoms of a substituent(s) of the substituted ZZ group. Herein,“YY” is larger than “XX.” “XX” and “YY” each mean an integer of 1 ormore.

In the exemplary embodiment, “XX to YY atoms” in the description of“substituted or unsubstituted ZZ group having XX to YY atoms” representatoms of an unsubstituted ZZ group and do not include atoms of asubstituent(s) of the substituted ZZ group. Herein, “YY” is larger than“XX.” “XX” and “YY” each mean an integer of 1 or more.

The same description as the above applies to “substituted orunsubstituted” in the following compound or a partial structure thereof.

In the first exemplary embodiment, when the substituents are mutuallybonded to form a cyclic structure, the cyclic structure is a saturatedring, unsaturated ring, aromatic hydrocarbon ring, or heterocyclic ring.

In the first exemplary embodiment, the aryl group and the heteroarylgroup as the linking group are exemplified by a divalent or multivalentgroup obtained by removing at least one atom from the above-describedmonovalent group.

In the first exemplary embodiment, the aromatic hydrocarbon ring and theheterocyclic ring are exemplified by a cyclic structure from which theabove-described monovalent group is derived.

Specific examples of the compound represented by the formula (1) areshown below, but the invention is not limited thereto.

Material for Organic Electroluminescence Device

A material for an organic electroluminescence device (occasionallyreferred to as an organic EL device material) according to the firstexemplary embodiment contains the compound according to the firstexemplary embodiment. The organic EL device material may contain onlythe compound according to the first exemplary embodiment or may containanother compound.

In the organic EL device material of the first exemplary embodiment, thecompound of the first exemplary embodiment to be contained is preferablya dopant material. In this arrangement, the organic EL device materialmay contain the compound of the first exemplary embodiment as the dopantmaterial and another compound such as a host material.

In the organic EL device material of the first exemplary embodiment, thecompound of the first exemplary embodiment to be contained is preferablya delayed fluorescence material.

Organic Electroluminescence Device

An organic EL device according to the first exemplary embodiment will bedescribed.

The organic EL device includes a pair of electrodes and an organic layerbetween the pair of electrodes. The organic layer includes a layerformed of an organic compound. The organic EL device according to theexemplary embodiment includes at least one organic layer. The organiccompound layer may further include an inorganic compound.

In the exemplary embodiment, at least one layer of the organic compoundlayer is an emitting layer. Accordingly, for instance, the organic layermay be provided by a single emitting layer. Alternatively, the organiclayer may be provided by layers applied in an organic EL device such asa hole injecting layer, a hole transporting layer, an electron injectinglayer, an electron transporting layer, a hole blocking layer and anelectron blocking layer. In the first exemplary embodiment, at least onelayer of the organic layer contains the above-described compound of thefirst exemplary embodiment.

The following are representative structure examples of an organic ELdevice:

-   -   (a) anode/emitting layer/cathode;    -   (b) anode/hole injecting⋅transporting layer/emitting        layer/cathode;    -   (c) anode/emitting layer/electron injecting⋅transporting        layer/cathode;    -   (d) anode/hole injecting⋅transporting layer/emitting        layer/electron injecting⋅transporting layer/cathode;    -   (e) anode/hole injecting⋅transporting layer/first emitting        layer/second emitting layer/electron injecting⋅transporting        layer/cathode; and    -   (f) anode/hole injecting⋅transporting layer/emitting        layer/blocking layer/electron injecting⋅transporting        layer/cathode.

While the arrangement (d) is preferably used among the abovearrangements, the arrangement of the invention is not limited to theabove arrangements.

It should be noted that the above-described “emitting layer” is anorganic layer generally employing a doping system and including a firstmaterial and a second material. In general, the first material promotesrecombination of electrons and holes and transmits excitation energygenerated by recombination to the second material. The first material isoften referred to as a host material. Accordingly, the first material isreferred to as the host material in descriptions hereinafter. Ingeneral, the second material receives the excitation energy from thehost material (the first material) to exhibit a high luminescentperformance. The second material is often referred to as a dopantmaterial or a guest material. Accordingly, the second material isreferred to as the dopant material in descriptions hereinafter. Thedopant material is preferably a compound having a high quantumefficiency.

The “hole injecting⋅transporting layer (hole injecting/transportinglayer)” means “at least one of a hole injecting layer and a holetransporting layer” while the “electron injecting⋅transporting layer(electron injecting/transporting layer)” means “at least one of anelectron injecting layer and an electron transporting layer.” Herein,when the hole injecting layer and the hole transporting layer areprovided, the hole injecting layer is preferably close to the anode.When the electron injecting layer and the electron transporting layerare provided, the electron injecting layer is preferably close to thecathode. Each of the hole injecting layer, hole transporting layer,electron transporting layer and electron injecting layer may be providedby a single layer or a plurality of layers.

The “hole injecting⋅transporting layer (hole injecting/transportinglayer)” means “at least one of a hole injecting layer and a holetransporting layer” while the “electron injecting⋅transporting layer(electron injecting/transporting layer)” means “at least one of anelectron injecting layer and an electron transporting layer.” Herein,when the hole injecting layer and the hole transporting layer areprovided, the hole injecting layer is preferably close to the anode.When the electron injecting layer and the electron transporting layerare provided, the electron injecting layer is preferably close to thecathode. Each of the hole injecting layer, hole transporting layer,electron transporting layer and electron injecting layer may be providedby a single layer or a plurality of layers.

The “hole injecting⋅transporting layer (hole injecting/transportinglayer)” means “at least one of a hole injecting layer and a holetransporting layer” while the “electron injecting⋅transporting layer(electron injecting/transporting layer)” means “at least one of anelectron injecting layer and an electron transporting layer.” Herein,when the hole injecting layer and the hole transporting layer areprovided, the hole injecting layer is preferably close to the anode.When the electron injecting layer and the electron transporting layerare provided, the electron injecting layer is preferably close to thecathode. Each of the hole injecting layer, hole transporting layer,electron transporting layer and electron injecting layer may be providedby a single layer or a plurality of layers.

The “hole injecting⋅transporting layer (hole injecting/transportinglayer)” means “at least one of a hole injecting layer and a holetransporting layer” while the “electron injecting⋅transporting layer(electron injecting/transporting layer)” means “at least one of anelectron injecting layer and an electron transporting layer.” Herein,when the hole injecting layer and the hole transporting layer areprovided, the hole injecting layer is preferably close to the anode.When the electron injecting layer and the electron transporting layerare provided, the electron injecting layer is preferably close to thecathode. Each of the hole injecting layer, hole transporting layer,electron transporting layer and electron injecting layer may be providedby a single layer or a plurality of layers.

The “hole injecting⋅transporting layer (hole injecting/transportinglayer)” means “at least one of a hole injecting layer and a holetransporting layer” while the “electron injecting⋅transporting layer(electron injecting/transporting layer)” means “at least one of anelectron injecting layer and an electron transporting layer.” Herein,when the hole injecting layer and the hole transporting layer areprovided, the hole injecting layer is preferably close to the anode.When the electron injecting layer and the electron transporting layerare provided, the electron injecting layer is preferably close to thecathode. Each of the hole injecting layer, hole transporting layer,electron transporting layer and electron injecting layer may be providedby a single layer or a plurality of layers.

The “hole injecting⋅transporting layer (hole injecting/transportinglayer)” means “at least one of a hole injecting layer and a holetransporting layer” while the “electron injecting⋅transporting layer(electron injecting/transporting layer)” means “at least one of anelectron injecting layer and an electron transporting layer.” Herein,when the hole injecting layer and the hole transporting layer areprovided, the hole injecting layer is preferably close to the anode.When the electron injecting layer and the electron transporting layerare provided, the electron injecting layer is preferably close to thecathode. Each of the hole injecting layer, hole transporting layer,electron transporting layer and electron injecting layer may be providedby a single layer or a plurality of layers.

The “hole injecting⋅transporting layer (hole injecting/transportinglayer)” means “at least one of a hole injecting layer and a holetransporting layer” while the “electron injecting⋅transporting layer(electron injecting/transporting layer)” means “at least one of anelectron injecting layer and an electron transporting layer.” Herein,when the hole injecting layer and the hole transporting layer areprovided, the hole injecting layer is preferably close to the anode.When the electron injecting layer and the electron transporting layerare provided, the electron injecting layer is preferably close to thecathode. Each of the hole injecting layer, hole transporting layer,electron transporting layer and electron injecting layer may be providedby a single layer or a plurality of layers.

The “hole injecting⋅transporting layer (hole injecting/transportinglayer)” means “at least one of a hole injecting layer and a holetransporting layer” while the “electron injecting⋅transporting layer(electron injecting/transporting layer)” means “at least one of anelectron injecting layer and an electron transporting layer.” Herein,when the hole injecting layer and the hole transporting layer areprovided, the hole injecting layer is preferably close to the anode.When the electron injecting layer and the electron transporting layerare provided, the electron injecting layer is preferably close to thecathode. Each of the hole injecting layer, hole transporting layer,electron transporting layer and electron injecting layer may be providedby a single layer or a plurality of layers.

In the first exemplary embodiment, when the compound of the firstexemplary embodiment is contained in an emitting layer 5, the emittinglayer 5 preferably contains no phosphorescent metal complex, morepreferably contains no metal complex other than a phosphorescent metalcomplex.

ΔST

In the first exemplary embodiment, it is preferable that a differenceΔST(D) between singlet energy S(D) of the compound and an energy gapT_(77K)(D) at 77K of the compound satisfies a numerical formula(Numerical Formula 1) below.ΔST(D)=S(D)−T _(77K)(D)<0.3 [eV]  (Numerical Formula 1).

ΔST(D) is preferably less than 0.2 [eV].

In the organic EL device material of the first exemplary embodiment, thecompound of the first exemplary embodiment that satisfies the aboveΔST(D) is preferably used.

Here, ΔST will be described.

In the organic EL device of the first exemplary embodiment, theabove-described compound of the first exemplary embodiment is used asthe dopant material. When a compound having a small energy difference(ΔST) between the singlet energy S and the triplet energy T is used asthe dopant material, the organic EL device emits light at a highefficiency in a high current density region.

From quantum chemical viewpoint, a decrease in the energy difference(ΔST) between the singlet energy S and the triplet energy T can beachieved by a small exchange interaction therebetween. Physical detailsof the relationship between ΔST and the exchange interaction aredescribed, for instance, in Reference Document 1 and Reference Document2 below.

Reference Document 1: Organic EL Symposium, proceeding for the tenthmeeting edited by Chihaya Adachi et al., S2-5, pp. 11-12

Reference Document 2: Organic Photochemical Reaction Theory edited byKatsumi Tokumaru, Tokyo Kagaku Dojin Co., Ltd. (1973).

Such a material can be synthesized according to molecular design basedon quantum calculation. Specifically, the material is a compound inwhich a LUMO electron orbit and a HOMO electron orbit are localized toavoid overlapping.

Examples of the compound having a small ΔST to be used as the dopantmaterial in the first exemplary embodiment are compounds in which adonor element is bonded to an acceptor element in a molecule and ΔST isin a range of 0 eV or more and less than 0.3 eV in terms ofelectrochemical stability (oxidation-reduction stability).

A more preferable compound is such a compound that dipoles formed in theexcited state of a molecule interact with each other to form anaggregate having a reduced exchange interaction energy. According toanalysis by the inventors, the dipoles are oriented substantially in thesame direction in the compound, so that ΔST can be further reduced bythe interaction of the molecules. In such a case, ΔST can be extremelysmall in a range of 0 eV to 0.2 eV.

TADF Mechanism

As described above, when ΔST(D) of the compound is small, inverseintersystem crossing from the triplet level of the compound to thesinglet level thereof is easily caused by heat energy given from theoutside. An energy state conversion mechanism to perform spin exchangefrom the triplet state of electrically excited excitons within theorganic EL device to the singlet state by inverse intersystem crossingis referred to as a TADF mechanism.

Currently, various arrangements of an organic EL device for emission bythe TADF mechanism has been proposed. For instance, use of a compoundhaving a small ΔST(D) as the host material and use of a compound havinga small ΔST(D) as the dopant material have been proposed.

In the organic EL device material of the first exemplary embodiment, itis preferable to use the compound having a small ΔST(D) as the hostmaterial or the dopant material. Inverse intersystem crossing from thetriplet energy level of the compound to the singlet energy level thereofis easily caused by heat energy given from the outside.

FIG. 2 shows a relationship in energy level between the host materialand the dopant material in the emitting layer in the use of the compoundhaving a small ΔST(D) as the dopant material. In FIG. 2 , S0 representsa ground state, S1_(H) represents the lowest singlet state of the hostmaterial, T1_(H) represents the lowest triplet state of the hostmaterial, S1_(D) represents the lowest singlet state of the dopantmaterial, and T1_(D) represents the lowest triplet state of the dopantmaterial. A dashed arrow represents energy transfer between the states.As shown in FIG. 2 , by using the compound having a small ΔST(D) as thedopant material, energy is transferred from the lowest triplet stateT1_(H) of the host material to the lowest singlet state S1_(D) or thelowest triplet state T1_(D) of the dopant material by Dexter transfer.Further, inverse intersystem crossing from the lowest triplet stateT1_(D) to the lowest singlet state S1_(D) of the dopant material ispossible by heat energy. As a result, fluorescent emission from thelowest singlet state S1_(D) of the dopant material can be observed. Itis inferred that the internal quantum efficiency can be theoreticallyraised up to 100% also by using delayed fluorescence by the TADFmechanism.

Relationship Between Triplet Energy T and T_(77K)

The above-described triplet energy T is different from a typicallydefined triplet energy. Such a difference will be described below.

The triplet energy is measured as follows. Firstly, a compound (ameasurement target) is deposited on a quartz substrate to prepare asample. As for this sample, the triplet energy is obtained by measuringthis sample at a low temperature (77K) in terms of phosphorescencespectrum expressed in coordinates of which the ordinate axis indicatesthe phosphorescence intensity and of which the abscissa axis indicatesthe wavelength, drawing a tangent to the rise of the phosphorescencespectrum on the shorter wavelength side, and calculating from apredetermined conversion equation based on a wavelength value at anintersection of the tangent and the abscissa axis.

Here, the compound used for the dopant material in the exemplaryembodiment is preferably the compound having a small ΔST(D) as describedabove. When ΔST(D) is small, intersystem crossing and inverseintersystem crossing are likely to occur even at a low temperature(77K), so that the singlet state and the triplet state coexist. As aresult, the spectrum to be measured in the same manner as the aboveincludes emission from both the singlet state and the triplet state.Although it is difficult to distinguish the emission from the singletstate from the emission from the triplet state, the value of the tripletenergy is basically considered dominant.

Accordingly, in the first exemplary embodiment, the spectrum is measuredby the same method as that for measuring a typical triplet energy T, butan amount of the triplet energy measured in the following manner isreferred to as an energy gap Eg_(77K) in order to differentiate themeasured energy from a typical triplet energy T in a strict meaning. Acompound (a measurement target) is deposited at a 100-nm film thicknesson a quartz substrate to prepare a sample. The energy gap T_(77K) ofthis sample is obtained by measuring this sample at a low temperature(77K) in terms of phosphorescence spectrum expressed in coordinates ofwhich the ordinate axis indicates the phosphorescence intensity and ofwhich the abscissa axis indicates the wavelength, drawing a tangent tothe rise of the phosphorescence spectrum on the shorter wavelength side,and calculating from the following conversion equation 1 based on awavelength value λ_(edge)[nm] at an intersection of the tangent and theabscissa axis.T _(77K) [eV]=1239.85/λ_(edge)  Conversion Equation 1:

The tangent to the rise of the phosphorescence spectrum on theshort-wavelength side is drawn as follows. While moving on a curve ofthe phosphorescence spectrum from the short-wavelength side to themaximum spectral value closest to the short-wavelength side among themaximum spectral values, a tangent is checked at each point on the curvetoward the long-wavelength of the phosphorescence spectrum. Aninclination of the tangent is increased as the curve rises (i.e., avalue of the ordinate axis is increased). A tangent drawn at a point ofthe maximum inclination (i.e., a tangent at an inflection point) isdefined as the tangent to the rise of the phosphorescence spectrum onthe short-wavelength side.

The maximum with peak intensity being 15% or less of the maximum peakintensity of the spectrum is not included in the above-mentioned maximumclosest to the short-wavelength side of the spectrum. The tangent drawnat a point of the maximum spectral value being closest to theshort-wavelength side and having the maximum inclination is defined as atangent to the rise of the phosphorescence spectrum on theshort-wavelength side.

For phosphorescence measurement, a spectrophotofluorometer body F-4500(manufactured by Hitachi High-Technologies Corporation) is usable. Themeasurement instrument is not limited to this arrangement. A combinationof a cooling unit, a low temperature container, an excitation lightsource and a light-receiving unit may be used for measurement.

Singlet Energy S

The singlet energy S is measured as follows.

A compound (a measurement target) is deposited at a 100-nm filmthickness on a quartz substrate to prepare a sample. An emissionspectrum of the sample is measured at a normal temperature (300K), thespectrum being expressed in coordinates of which the ordinate axisindicates luminous intensity and of which the abscissa axis indicatesthe wavelength. A tangent is drawn to the rise of the emission spectrumon the short-wavelength side. The singlet energy S is calculated fromthe following conversion equation 2 based on a wavelength valueλ_(edge)[nm] at an intersection of the tangent and the abscissa axis.S [eV]=1239.85/λ_(edge)  Conversion Equation 2:

Absorption spectrum is measured by a spectrophotometer. For instance, aspectrophotometer (product name: U3310) manufactured by Hitachi, Ltd. isusable.

The tangent to the rise of the emission spectrum on the short-wavelengthside is drawn as follows. While moving on a curve of the emissionspectrum from the short-wavelength side to the maximum spectral valueclosest to the short-wavelength side among the maximum spectral values,a tangent is checked at each point on the curve toward thelong-wavelength of the emission spectrum. An inclination of the tangentis increased as the curve rises (i.e., a value of the ordinate axis isincreased). A tangent drawn at a point of the maximum inclination (i.e.,a tangent at an inflection point) is defined as the tangent to the riseof the emission spectrum on the short-wavelength side.

The maximum with peak intensity being 15% or less of the maximum peakintensity of the spectrum is not included in the above-mentioned maximumclosest to the short-wavelength side of the spectrum. The tangent drawnat a point of the maximum spectral value being closest to theshort-wavelength side and having the maximum inclination is defined as atangent to the rise of the emission spectrum on the short-wavelengthside.

In the first exemplary embodiment, a difference between the singletenergy S and the energy gap T_(77K) is defined as ΔST. Accordingly, inthe first exemplary embodiment, ΔST(D) of the dopant material ispreferably represented by Numerical Formula (1) above.

Host Material in Emitting Layer

When the compound of the first exemplary embodiment is used as thedopant material, the host material preferably has a larger triplet levelthan that of the compound of the first exemplary embodiment. Examples ofthe compound suitable for the host material include an aromatichydrocarbon derivative, heterocyclic derivative, arylamine derivative,porphyrin compound, various metal complexes, phosphorus compound andhigh-molecular compound. Specific examples of the compound suitable forthe host material include compounds below.

Examples of the aromatic hydrocarbon derivative include compounds havinga high triplet level such as benzene, naphthalene, phenanthrene,triphenylene and fluorene.

Examples of the heterocyclic derivative include: a pyrrole derivative,indole derivative, carbazole derivative, furan derivative, benzofuranderivative, dibenzofuran derivative, thiophene derivative,benzothiophene derivative, dibenzothiophene derivative, triazolederivative, oxazole derivative, oxadiazole derivative, imidazolederivative, benzimidazole derivative, imidazopyridine derivative, andindolizine derivative.

Examples of the porphyrin compound include a compound such as aphthalocyanine derivative.

Examples of the metal complexes include a metal complex of a quinolinolderivative and a metal complex having phthalocyanine, benzoxazole andbenzothiazole as a ligand.

Examples of the phosphorus compound include a compound such as phosphineoxide.

Examples of the high-molecular compound include a poly(N-vinylcarbazole)derivative, aniline copolymer, thiophene oligomer, conductive polymeroligomer such as polythiophene, polythiophene derivative, polyphenylenederivative, polyphenylenevinylene derivative, and polyfluorenederivative.

As the host material, one of the various compounds may be used alone, oralternatively, two or more thereof may be used in combination.

Dopant Material in Emitting Layer

When the compound of the first exemplary embodiment is used as the hostmaterial, for instance, the following fluorescent material is usable asthe dopant material.

An aromatic amine derivative and the like are usable as a greenfluorescent material. Specific examples of the green fluorescentmaterial includeN-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3-amine(abbreviation: 2PCAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine(abbreviation: 2PCABPhA),N-(9,10-diphenyl-2-anthryl)-N,N′,N′-triphenyl-1,4-phenylene diamine(abbreviation: 2DPAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPABPhA),N-[9,10-bis(1,1′-biphenyl-2-yl)]-N-[4-(9H-carbazole-9-yl)phenyl]-N-phenylanthracene-2-amine(abbreviation: 2YGABPhA), and N,N,9-triphenylanthracene-9-amine(abbreviation: DPhAPhA).

A tetracene derivative, diamine derivative and the like are usable as ared fluorescent material. Specific examples of the red fluorescentmaterial includeN,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation:p-mPhTD), and7,14-diphenyl-N,N,N′,N′-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine(abbreviation: p-mPhAFD).

In the first exemplary embodiment, the energy gap T_(77K)(H1) at 77K ofthe compound usable as the host material is preferably larger than theenergy gap T_(77K)(D) at 77K of the compound usable as the dopantmaterial.

The thickness of the emitting layer is preferably in a range from 5 nmto 50 nm, more preferably from 7 nm to 50 nm, further preferably from 10nm to 50 nm. The thickness of less than 5 nm may cause difficulty informing the emitting layer and in controlling chromaticity, while thethickness of more than 50 nm may raise drive voltage.

In the emitting layer, a ratio of the host material and the dopantmaterial is preferably in a range of 99:1 to 50:50 at a mass ratio.

Substrate

A substrate is used as a support for the organic EL device. Forinstance, glass, quartz, plastics and the like are usable as thesubstrate. A flexible substrate is also usable. The flexible substrateis a bendable substrate, which is exemplified by a plastic substrateformed of polycarbonate, polyarylate, polyethersulfone, polypropylene,polyester, polyvinyl fluoride, and polyvinyl chloride. Moreover, aninorganic vapor deposition film is also usable.

Anode

Metal, alloy, an electrically conductive compound and a mixture thereof,which have a large work function, specifically, of 4.0 eV or more, ispreferably usable as the anode formed on the substrate. Specificexamples of the material for the anode include indium tin oxide (ITO),indium tin oxide containing silicon or silicon oxide, indium zinc oxide,tungsten oxide, indium oxide containing zinc oxide and graphene. Inaddition, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chrome(Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium(Pd), titanium (Ti), or nitrides of a metal material (e.g., titaniumnitride) are usable.

The above materials are typically deposited as a film by sputtering. Forinstance, indium zinc oxide can be deposited as a film by sputteringusing a target that is obtained by adding zinc oxide in a range from 1mass % to 10 mass % to indium oxide. Moreover, for instance, indiumoxide containing tungsten oxide and zinc oxide can be deposited as afilm by sputtering using a target that is obtained by adding tungstenoxide in a range from 0.5 mass % to 5 mass % and zinc oxide in a rangefrom 0.1 mass % to 1 mass % to indium oxide. In addition, vapordeposition, coating, ink jet printing, spin coating and the like may beused for forming a film.

Among EL layers formed on the anode, a hole injecting layer formedadjacent to the anode is formed of a composite material that facilitatesinjection of holes irrespective of the work function of the anode.Accordingly, a material usable as an electrode material (e.g., metal,alloy, an electrically conductive compound, a mixture thereof, andelements belonging to Groups 1 and 2 of the periodic table of theelements) is usable as the material for the anode.

The elements belonging to Groups 1 and 2 of the periodic table of theelements, which are materials having a small work function, namely, analkali metal such as lithium (Li) and cesium (Cs) and an alkaline earthmetal such as magnesium (Mg), calcium (Ca) and strontium (Sr), alloythereof (e.g., MgAg, AlLi), a rare earth metal such as europium (Eu) andytterbium (Yb), and alloy thereof are also usable as the material forthe anode. When the anode is formed of the alkali metal, alkaline earthmetal and alloy thereof, vapor deposition and sputtering are usable.Further, when the anode is formed of silver paste and the like, coating,ink jet printing and the like are usable.

Cathode

Metal, alloy, an electrically conductive compound, a mixture thereof andthe like, which have a small work function, specifically, of 3.8 eV orless, is preferably usable as a material for the cathode. Specificexamples of the material for the cathode include: the elements belongingto Groups 1 and 2 of the periodic table of the elements, namely, analkali metal such as lithium (Li) and cesium (Cs) and an alkaline earthmetal such as magnesium (Mg), calcium (Ca) and strontium (Sr); alloythereof (e.g., MgAg, AlLi); a rare earth metal such as europium (Eu) andytterbium (Yb); and alloy thereof.

When the cathode is formed of the alkali metal, alkaline earth metal andalloy thereof, vapor deposition and sputtering are usable. Moreover,when the anode is formed of silver paste and the like, coating, ink jetprinting and the like are usable.

By providing an electron injecting layer, various conductive materialssuch as Al, Ag, ITO, graphene and indium tin oxide containing silicon orsilicon oxide are usable for forming the cathode irrespective of themagnitude of the work function. The conductive materials can bedeposited as a film by sputtering, ink jet printing, spin coating andthe like.

Hole Injecting Layer

A hole injecting layer is a layer containing a highly hole-injectablesubstance. Examples of the highly hole-injectable substance includemolybdenum oxide, titanium oxide, vanadium oxide, rhenium oxide,ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide,tantalum oxide, silver oxide, tungsten oxide, and manganese oxide.

In addition, the examples of the highly hole-injectable substancefurther include an aromatic amine compound that is a low-molecularcompound such 4,4′,4″-tris(N,N-diphenylamino)triphenylamine(abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA),4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl(abbreviation:DPAB),4,4′-bis(N-{4-[N′-(3-methylphenyl)-N′-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD),1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B),3-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1),3,6-bis[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2), and3-[N-(1-naphthyl)-N-(9-phenylcarbazole-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1).

Moreover, a high-molecular compound (e.g., an oligomer, dendrimer andpolymer) is also usable as the highly hole-injectable substance.Examples of the high-molecular compound include poly(N-vinylcarbazole)(abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylamido] (abbreviation: PTPDMA), andpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation:Poly-TPD). Furthermore, the examples of the high-molecular compoundinclude a high-molecular compound added with an acid such aspoly(3,4-ethylene dioxythiophene)/poly(styrene sulfonic acid)(PEDOT/PSS), and polyaniline/poly(styrene sulfonic acid) (PAni/PSS).

Hole Transporting Layer

A hole transporting layer is a layer containing a highlyhole-transportable substance. An aromatic amine compound, carbazolederivative, anthracene derivative and the like are usable for the holetransporting layer. Specific examples of a material for the holetransporting layer include4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB),N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD), 4-phenyl-4′-(9-phenylfluorene-9-yl)triphenylamine(abbreviation: BAFLP),4,4′-bis[N-(9,9-dimethylfluorene-2-yl)-N-phenylamino]biphenyl(abbreviation: DFLDPBi), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine(abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA), and4,4′-bis[N-(spiro-9,9′-bifluorene-2-yl)-N-phenylamino]biphenyl(abbreviation: BSPB). The above-described substances mostly have a holemobility of 10⁻⁶ cm²/Vs or more.

A carbazole derivative such as CBP, CzPA and PCzPA and an anthracenederivative such as t-BuDNA, DNA, DPAnth may be used for the holetransporting layer. Moreover, a high-molecular compound such aspoly(N-vinylcarbazole) (abbreviation: PVK) andpoly(4-vinyltriphenylamine) (abbreviation: PVTPA) is also usable.

However, any substance having a hole transporting performance higherthan an electron transporting performance may be used in addition to theabove substances. A a highly hole-transportable substance may beprovided by a single layer or a laminated layer of two layers or moreformed of the above substance.

Electron Transporting Layer

An electron transporting layer is a layer containing a highlyelectron-transportable substance. As the electron transporting layer, 1)a metal complex such as an aluminum complex, beryllium complex and zinccomplex, 2) heteroaromatic compound such as an imidazole derivative,benzimidazole derivative, azine derivative, carbazole derivative, andphenanthroline derivative, and 3) a high-molecular compound are usable.Specifically, as a low-molecular organic compound, a metal complex suchas Alq, tris(4-methyl-8-quinolinato)aluminum (abbreviation: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq₂), BAlq,Znq, ZnPBO and ZnBTZ are usable. In addition to the metal complex, aheteroaromatic compound such as2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(ptert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene(abbreviation: OXD-7),3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenyl)-1,2,4-triazole(abbreviation: TAZ),3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenyl)-1,2,4-triazole(abbreviation: p-EtTAZ), bathophenanthroline (abbreviation: BPhen),bathocuproine (abbreviation: BCP), and4,4′-bis(5-methylbenzoxazole-2-yl)stilbene (abbreviation: BzOs) areusable. The above-described substances mostly have an electron mobilityof 10⁻⁶ cm²/Vs or more. However, any substance having an electrontransporting performance higher than a hole transporting performance maybe used for the electron transporting layer in addition to the abovesubstances. The electron transporting layer may be provided by a singlelayer or a laminated layer of two layers or more formed of the abovesubstances.

Moreover, a high-molecular compound is also usable for the electrontransporting layer. For instance,poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)](abbreviation: PF-Py),poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)](abbreviation: PF-BPy) and the like are usable.

Electron Injecting Layer

An electron injecting layer is a layer containing a highlyelectron-injectable substance. Examples of a material for the electroninjecting layer include an alkali metal, alkaline earth metal and acompound thereof, examples of which include lithium (Li), cesium (Cs),calcium (Ca), lithium fluoride (LiF), cesium fluoride (CsF), calciumfluoride (CaF2), and lithium oxide (LiOx). In addition, a compoundcontaining an alkali metal, alkaline earth metal and a compound thereofin the electron transportable substance, specifically, a compoundcontaining magnesium (Mg) in Alq and the like may be used. With thiscompound, electrons can be more efficiently injected from the cathode.

Alternatively, a composite material provided by mixing an organiccompound with an electron donor may be used for the electron injectinglayer. The composite material exhibits excellent electron injectingperformance and electron transporting performance since the electrondonor generates electrons in the organic compound. In this arrangement,the organic compound is preferably a material exhibiting an excellenttransporting performance of the generated electrons. Specifically, forinstance, the above-described substance for the electron transportinglayer (e.g., the metal complex and heteroaromatic compound) is usable.The electron donor may be any substance exhibiting an electron donatingperformance to the organic compound. Specifically, an alkali metal,alkaline earth metal and a rare earth metal are preferable, examples ofwhich include lithium, cesium, magnesium, calcium, erbium and ytterbium.Moreover, an alkali metal oxide and alkaline earth metal oxide arepreferable, examples of which include lithium oxide, calcium oxide, andbarium oxide. Further, Lewis base such as magnesium oxide is alsousable. Furthermore, tetrathiafulvalene (abbreviation: TTF) is alsousable.

Layer Formation Method(s)

A method for forming each layer of the organic EL device is subject tono limitation except for the above particular description. However,known methods of dry film-forming such as vacuum deposition, sputtering,plasma or ion plating and wet film-forming such as spin coating,dipping, flow coating or ink-jet are applicable.

Thickness

The thickness of each organic layer of the organic EL device in theexemplary embodiment is subject to no limitation except for thethickness particularly described above. However, the thickness istypically preferably in a range of several nanometers to 1 μm because anexcessively thin film is likely to entail defects such as a pin holewhile an excessively thick film requires high applied voltage anddeteriorates efficiency.

Modifications of Embodiment(s)

It should be noted that the invention is not limited to the aboveexemplary embodiment but may include any modification and improvement aslong as such modification and improvement are compatible with theinvention.

The emitting layer is not limited to a single layer, but may be providedas laminate by a plurality of emitting layers. When the organic ELdevice includes a plurality of emitting layers, it is only required thatat least one of the emitting layers includes the compound represented bythe formula (1). The others of the emitting layers may be a fluorescentemitting layer or a phosphorescent emitting layer.

When the organic EL device includes the plurality of emitting layers,the plurality of emitting layers may be adjacent to each other or aso-called tandem organic EL device in which a plurality of emittingunits are laminated through an intermediate layer.

An arrangement in which the plurality of emitting layers are laminatedis exemplified by an organic EL device 1A shown in FIG. 3 . The organicEL device 1A includes an organic layer 10A. The organic layer 10A isdifferent from the organic EL device 1 shown in FIG. 1 in including afirst emitting layer 51 and a second emitting layer 52 between a holeinjecting/transporting layer 6 and an electron injecting/transportinglayer 7. At least one of the first emitting layer 51 and the secondemitting layer 52 contains the compound represented by the formula (1).Except for the above point, the organic EL device 1A is arranged in thesame manner as the organic EL device 1.

For instance, an electron blocking layer may be provided adjacent to aside of the emitting layer near the anode and a hole blocking layer maybe provided adjacent to a side of the emitting layer near the cathode.With this arrangement, electrons and holes can be confined in theemitting layer, thereby enhancing probability of exciton generation inthe emitting layer.

The organic EL device according to the first exemplary embodiment isusable for a display unit and electronic equipment such as alight-emitting unit. Examples of the display unit include a displaycomponent (e.g., en organic EL panel module), TV, mobile phone, tabletand personal computer. Examples of the light-emitting unit include anilluminator and a vehicle light.

Further, specific arrangements and configurations for practicing theinvention may be altered to other arrangements and configurations aslong as such other arrangements and configurations are compatible withthe invention.

EXAMPLES

Examples of the invention will be described below. However, theinvention is not limited by these Examples.

Example 1: Synthesis of Compound 1

A synthesis scheme of a compound 1 is shown below.

(1-1) Synthesis of 1-(2-nitrophenyl)naphthalene

Under nitrogen atmosphere, 18.5 g of 1-naphthaleneboronic acid, 18.2 gof 1-bromo-2-nitrobenzene, 3.12 g oftetrakis(triphenylphosphine)palladium(0), 144 mL of toluene, 144 mL of1,2-dimethoxyethane, and 150 mL of 2M sodium carbonate aqueous solutionwere put into a flask and heated to reflux for nine hours while beingstirred. After cooled down to the room temperature, the reactionsolution was filtered and a solvent was distilled away under reducedpressure. The obtained residue was refined by silica-gel columnchromatography, whereby 19.9 g (yield 89%) of a light yellow solid of1-(2-nitrophenyl)naphthalene was obtained. It should be noted that1,2-dimethoxyethane is occasionally abbreviated as DME.

(1-2) Synthesis of Intermediate (A)

Under nitrogen atmosphere, 19.9 g of 1-(2-nitrophenyl)naphthalene, 52.2g of triphenylphosphine, and 163 mL of ortho-dichlorobenzene were putinto a flask and heated to reflux for 32 hours while being stirred.After cooled down to the room temperature, the reaction solution wasfiltered and a solvent was distilled away under reduced pressure. Theobtained residue was refined by silica-gel column chromatography,whereby 15.4 g (yield 90%) of a yellow solid of an intermediate (A) wasobtained. It should be noted that ortho-dichlorobenzene is occasionallyabbreviated as o-DCB.

(1-3) Synthesis of Compound 1

Under nitrogen atmosphere, 15.4 g of the intermediate (A), 6.64 g of2,5-dichloroterephthalonitrile, 10.2 g of potassium carbonate, 112 mL ofN-methyl-2-pyrrolidinone were put into a flask and stirred at 100degrees C. for six hours and subsequently at 150 degrees C. for ninehours. After cooled down to the room temperature, the reaction solutionwas extracted with toluene. After an aqueous layer was removed, anorganic layer was washed with a saturated ammonium chloride aqueoussolution. After dried with magnesium sulfate, the organic layer wasconcentrated. The obtained residue was refined by silica-gel columnchromatography, whereby 5.27 g (yield 28%) of a yellow solid of acompound 1 was obtained. It should be noted thatN-methyl-2-pyrrolidinone is occasionally abbreviated as NMP.

Example 2: Synthesis of Compound 2

A synthesis scheme of a compound 2 is shown below.

(2-1) Synthesis of 2-bromo-4-(9-carbazolyl)-1-nitrobenzene

Under nitrogen atmosphere, 7.52 g of carbazole, 11.8 g of2-bromo-4-fluoro-1-nitrobenzen, 15.0 g of potassium carbonate and 150 mLof N,N-dimethylformamide were put into a flask and heated to reflux for24 hours while being stirred. After cooled down to the room temperature,the reaction solution was extracted with toluene. After an aqueous layerwas removed, an organic layer was washed with a saturated ammoniumchloride aqueous solution. After dried with magnesium sulfate, theorganic layer was concentrated and washed with methanol, whereby 14.2 g(yield 86%) of a yellow orange solid of2-bromo-4-(9-carbazolyl)-1-nitrobenzene was obtained. It should be notedthat N,N-dimethylformamide is occasionally abbreviated as DMF.

(2-2) Synthesis of 1-[2-nitro-5-(9-carbazolyl)phenyl]naphthalene

1-[2-nitro-5-(9-carbazolyl)phenyl]naphthalene was synthesized in thesame manner as in the synthesis (1-1) of 1-(2-nitrophenyl)naphthalene,except for using 2-bromo-4-(9-carbazolyl)-1-nitrobenzene in place of1-bromo-2-nitrobenzene.

(2-3) Synthesis of Intermediate (B)

An intermediate (B) was synthesized in the same manner as in thesynthesis (1-2) of the intermediate (A), except for using1-[2-nitro-5-(9-carb azolyl)phenyl]naphthalene in place of1-(2-nitrophenyl]naphthalene.

(2-4) Synthesis of Compound 2

A compound 2 was synthesized in the same manner as in the synthesis(1-3) of the compound 1, except for using the intermediate (B) in placeof the intermediate (A).

Example 3: Synthesis of Compound 3

A synthesis scheme of a compound 3 is shown below.

(3-1) Synthesis of 2-dibenzofuranyl-1-nitrobenzene

2-dibenzofuranyl-1-nitrobenzene was synthesized in the same manner as inthe synthesis (1-1) of 1-(2-nitrophenyl)naphthalene, except for using4-dibenzofuran boronic acid in place of 1-naphthaleneboronic acid.

(3-2) Synthesis of Intermediate (D)

Under nitrogen atmosphere, 2-dibenzofuranyl-1-nitrobenzene of 24.0 g,triphenyl phosphine of 54.4 g and N,N-dimethylacetamide of 166 mL wereput into a flask and heated to reflux for 20 hours while being stirred.After cooled down to the room temperature, the reaction solution wasextracted with dichloromethane. After an aqueous layer was removed, anorganic layer was washed with a saturated ammonium chloride aqueoussolution. After dried with magnesium sulfate, the organic layer wasconcentrated. The obtained residue was refined by silica-gel columnchromatography, whereby 14.5 g (yield 68%) of a white solid of anintermediate (D) was obtained. It should be noted thatN,N-dimethylacetamide is occasionally abbreviated as DMAc.

(3-3) Synthesis of Compound 3

A compound 3 was synthesized in the same manner as in the synthesis(1-3) of the compound 1, except for using the intermediate (D) in placeof the intermediate (A).

Evaluation of Compounds

Next, fluorescence spectra of the compounds used in Example weremeasured. The target compounds are the compound 1 and a referencecompound 1 shown below. A measurement method or a calculation method isdescribed below. Measurement results or calculation results are shown inTable 1.

Each of the compounds was dissolved in a solvent to prepare a sample formeasuring fluorescence spectra. The solvent was toluene in aspectroscopic grade. A concentration of each of the compounds formeasuring fluorescence spectra was set at 5.0 [μmol/liter].

Each of the samples for measuring fluorescence spectra was put into aquartz cell and irradiated with excitation light at a room temperature(300 K), thereby measuring fluorescence intensity. The compound 1 wasirradiated with excitation light having a 350-nm wavelength. Thereference compound 1 was irradiated with excitation light having a360-nm wavelength.

The fluorescence spectra were expressed in coordinates of which ordinateaxis indicated the fluorescence intensity and of which abscissa axisindicated the wavelength.

For fluorescence spectra measurement, a spectrophotofluorometer bodyF-4500 (manufactured by Hitachi High-Technologies Corporation) was used.

A wavelength in which the fluorescence intensity was at the maximum(referred to as a main peak wavelength in the invention) λ_(F) wascalculated based on the obtained fluorescence spectra. The results areshown in Table 1.

As a result, it is revealed that the compound 1 forming a cyclicstructure emits light in longer wavelength regions as compared with thereference compound 1.

TABLE 1 Compound 1 Reference Compound 1 λ_(F) (nm) 512 473Transitional PL Measurement

A transitional PL measurement sample 1 and a transitional PL measurementsample 2 were prepared. Specifically, a co-deposition film was formed ona quartz substrate using a vapor deposition apparatus so as to have acomposition and film thickness described below.

Transitional PL Measurement Sample 1

Composition: The transitional PL measurement sample 1 was provided bydoping a compound PB with 12 mass % of the compound 1.

-   -   Film Thickness: 100 nm

Transitional PL Measurement Sample 2

-   -   Composition: The transitional PL measurement sample 2 was        provided by doping the compound PB with 12 mass % of the        reference compound 1.    -   Film Thickness: 100 nm

Emission lifetime of each of the compound 1 of the transitional PLmeasurement sample 1 and the reference compound 1 of the transitional PLmeasurement sample 2 was measured using a transitional fluorescencelife-time measuring instrument and a picosecond pulse laser instrument.A fluorescence life-time measuring instrument C4780 (manufactured byHamamatsu Photonics K.K.) was used as the transitional fluorescencelife-time measuring instrument. Using a nitrogen laser MNL 200(manufactured by LTB Lasertechnik Berlin GmbH) as the picosecond pulselaser instrument, picosecon pulse laser with a wavelength of 337 nm, anoutput of 2 mJ/pulse and a pulse width of about 700 ps was emitted.

As a result of the measurement, it is revealed that a delayed emissioncomponent with a microsecond lifetime exists in emission obtained fromeach of the compound 1 and the reference compound 1.

Accordingly, it is revealed from the above results that the compound 1forming a cyclic structure emits light by the TADF mechanism in longerwavelength regions as compared with the reference compound 1.

Example 4: Synthesis of Compound 4

A synthesis scheme of a compound 4 is shown below.

Under nitrogen atmosphere, 16.2 g of the intermediate (D), 4.92 g of4.5-difluorophthalonitrile, 9.12 g of potassium carbonate, 120 mL ofN-methyl-2-pyrrolidinone were put into a flask and stirred at the roomtemperature for 10 hours. Water was added to the reaction solution. Theobtained solution was filtered to obtain a deposited solid. The obtaineddeposited solid was washed with toluene, whereby 3.25 g (yield 17%) of ayellow solid of the compound 4 was obtained.

Example 5: Synthesis of Compound 5

A synthesis scheme of a compound 5 is shown below.

(5-1) Synthesis of Intermediate (E)

Under nitrogen atmosphere, 119 g of 1,4-dibromo-2,5-difluorobenzene, 117g of copper cyanide (I) and 730 mL of N,N-dimethylformamide were putinto a flask and heated to reflux for 16 hours while being stirred.After cooled down to the room temperature, the reaction solution wasadded to ammonia water and extracted with dichloromethane. The organiclayer was concentrated. The obtained residue was refined by silica-gelcolumn chromatography and washing with heptane, whereby 46.0 g (yield64%) of a white solid of an intermediate (E) was obtained.

(5-2) Synthesis of N-(2-chlorophenyl)-9,9-dimethyl-fluorene-2-amine

Under nitrogen atmosphere, 30.0 g of 2-dibromo-9,9-dimethylfluorene,15.0 mL of 2-chloroaniline, 0.300 g of palladium(II) acetate, 0.478 g oftri-tert-butylphosphoniumtetrafluoroborate, 27.0 g ofsodium-tert-butoxide, and 1.00 L of toluene were put into a flask andheated to reflux for eight hours while being stirred. Under nitrogenatmosphere, 0.100 g of palladium(II) acetate and 0.300 g of1,1′-bis(diphenylphosphino)ferrocene were added and heated to reflux forthree hours while being stirred. After cooled down to the roomtemperature, the reaction solution was extracted with toluene. After anaqueous layer was removed, an organic layer was washed with a saturatedsaline solution. After dried with sodium sulfate, the organic layer wasconcentrated. The obtained residue was refined by silica-gel columnchromatography and recrystallization, whereby 25.0 g (yield 71%) of awhite solid of N-(2-chlorophenyl)-9,9-dimethyl-fluorene-2-amine wasobtained.

(5-3) Synthesis of Intermediate (F)

Under nitrogen atmosphere, 25.0 g ofN-(2-chlorophenyl)-9,9-dimethyl-fluorene-2-amine, 3.50 g ofpalladium(II) acetate, 7.70 g ofdi-tert-butyl(methyl)phosphoniumtetrafluoroborate, 127 g of cesiumcarbonate, and 600 mL of N,N-dimethylacetoamide were put into a flaskand heated to reflux for seven hours while being stirred. After cooleddown to the room temperature, the reaction solution was extracted withethyl acetate. After an aqueous layer was removed, an organic layer waswashed with a saturated saline solution. After dried with sodiumsulfate, the organic layer was concentrated. The obtained residue wasrefined by silica-gel column chromatography and recrystallization,whereby 16.3 g (yield 73%) of a brown solid of an intermediate (F) wasobtained.

(5-4) Synthesis of Compound 5

Under nitrogen atmosphere, 0.755 g of the intermediate (E), 2.75 g ofthe intermediate (F), 1.40 g of potassium carbonate, 18 mL ofN-methyl-2-pyrrolidinone were put into a flask and stirred at the roomtemperature for 10 hours. The reaction solution was added with water.The deposited solid was the organic layer was concentrated. The obtainedresidue was refined by silica-gel column chromatography and washed withtoluene, whereby 1.60 g (yield 50%) of a yellow solid of a compound 5was obtained.

Example 6: Synthesis of Compound 6

A synthesis scheme of a compound 6 is shown below.

(6-1) Synthesis of 2-bromo-4-(9-carbazolyl)-1-nitrobenzene

2-bromo-4-(9-carbazolyl)-1-nitrobenzene was synthesized in the samemanner as in the synthesis (2-1).

(6-2) Synthesis of 4-[2-nitro-5-(9-carbazolyl)phenyl]dibenzofuran

4-[2-nitro-5-(9-carbazolyl)phenyl]dibenzofuran was synthesized in thesame manner as in the synthesis (1-1) of 1-(2-nitrophenyl)naphthalene,except for using 4-dibenzofuranboronic acid in place of1-naphthaleneboronic acid and using2-bromo-4-(9-carbazolyl)-1-nitrobenzene in place of1-bromo-2-nitrobenzene.

(6-3) Synthesis of Intermediate (G)

An intermediate (G) was synthesized in the same manner as in thesynthesis (1-2) of the intermediate (A), except for using4-[2-nitro-5-(9-carbazolyl)phenyl]dibenzofuran in place of1-(2-nitrophenyl]naphthalene.

(6-4) Synthesis of Compound 6

A compound 6 was synthesized in the same manner as in the synthesis(5-4) of the compound 5, except for using 4-fluorophthalonitrile inplace of the intermediate (E) and using the intermediate (G) in place ofthe intermediate (F).

Example 7: Synthesis of Compound 7

A synthesis scheme of a compound 7 is shown below.

(7-1) Synthesis of Intermediate (H)

Under nitrogen atmosphere, 1.08 g of sodium hydride, 72 mL of THF(tetrahydrofuran), and 2.10 g of carbazole were put into a flask andstirred at the room temperature for one hour. The obtained reactionsolution was dropped into a flask containing 2.07 g of4,5-difluorophthalonitrile, and 36 mL of THF and was stirred at the roomtemperature for six hours. The reaction solution was extracted withtoluene. After an aqueous layer was removed, an organic layer was washedwith a saturated ammonium chloride aqueous solution. After dried withmagnesium sulfate, the organic layer was concentrated. The obtainedresidue was refined by silica-gel column chromatography, whereby 1.43 g(yield 51%) of a white solid of an intermediate (H) was obtained.

(7-2) Synthesis of Compound 7

A compound 7 was synthesized in the same manner as in the synthesis(5-4) of the compound 5, except for using the intermediate (H) in placeof the intermediate (E) and using the intermediate (G) in place of theintermediate (F).

Example 8: Synthesis of Compound 8

A synthesis scheme of a compound 8 is shown below.

(8-1) Synthesis of Compound 8

A compound 8 was synthesized in the same manner as in the synthesis(7-1) of the intermediate (H), except for using the intermediate (D) inplace of carbazole and using terefluoroisophthalonitrile in place of4,5-difluorophthalonitrile.

Example 9: Synthesis of Compound 9

A synthesis scheme of a compound 9 is shown below.

(9-1) Synthesis of dibenzofuran-4,6-diboronic acid

Under argon atmosphere, 30.0 g of dibenzofuran, 81.0 mL ofN,N,N′,N′-tetramethylethylenediamine, and 105 mL of diethylether wereput into a flask and cooled to minus 78 degrees C. After the cooling,417 mL of sec-butyllithium was dropped in the flask and stirred at theroom temperature for 24 hours. After the stirring, the reaction solutionwas again cooled to minus 78 degrees C. Subsequently, 181 mL of trimelylborate was dropped in the flask and stirred at the room temperature for12 hours. After the stirring, 6N-hydrochloric acid was added to theflask. Subsequently, suction filtration was performed. The obtainedsubstance by filtration and an organic layer of the filtrate were mixed.6N-aqueous sodium hydroxide was added to the mixture. After the6N-aqueous sodium hydroxide was added, the obtained aqueous layer waswashed with diethylether and added with concentrated hydrochloric acidto obtain deposit. The obtained deposit was subjected to suctionfiltration. The filtrated deposit was washed with water, dried withsodium sulfate, concentrated and washed with ethyl acetate. The obtainedresidue was refined by recrystallization, whereby 22.0 g (yield 48%) ofa white solid of dibenzofuran-4,6-diboronic acid was obtained. It shouldbe noted that N,N,N′,N′-tetramethylethylenediamine is occasionallyabbreviated as TMEDA.

(9-2) Synthesis of 4,6-di(2-nitrophenyl)dibenzofuran

Under argon atmosphere, 38.2 g of 1-bromo-2-nitrobenzene, 22.0 g ofdibenzofuran-4,6-diboronic acid, 3.96 g oftetrakis(triphenylphosphine)palladium(0), 26.4 mL of 2M-sodium hydrogencarbonate aqueous solution, and 31.0 mL of 1,4-dioxane were put into aflask and heated at 80 degrees C. for 39 hours while being stirred.After cooled down to the room temperature, the reaction solution wasrefined by silica-gel column chromatography and further byrecrystallization, whereby 23.5 g (yield 67%) of a white solid of4.6-di(2-nitrophenyl)dibenzofuran was obtained.

(9-3) Synthesis of 5,10-dihydrofuro[3,2-c:4,5-c′]dicarbazole

5,10-dihydrofuro[3,2-c:4,5-c′]dicarbazole was synthesized in the samemanner as in the synthesis (1-2) of the intermediate (A), except forusing 4,6-di(2-nitrophenyl)dibenzofuran in place of1-(2-nitrophenyl]naphthalene.

(9-4) Synthesis of Intermediate (I)

Under argon atmosphere, 7.27 g of5,10-dihydrofuro[3,2-c:4,5-c′]dicarbazole, 4.28 g of iodobenzene, 1.25 gof copper powder, 4.07 g of potassium carbonate and 29.4 mL ofN,N-dimethylformamide were put into a flask and heated for 18 hourswhile being stirred. After cooled down to the room temperature, thereaction solution was refined by silica-gel column chromatography,further by recrystallization, still further by suspension and washing,whereby 1.02 g (yield 25%) of an intermediate (I) was obtained.

(9-5) Synthesis of Compound 9

A compound 6 was synthesized in the same manner as in the synthesis(5-4) of the compound 5, except for using 4-fluorophthalonitrile inplace of the intermediate (E) and using the intermediate (I) in place ofthe intermediate (F).

Example 10: Synthesis of Compound 10

A synthesis scheme of a compound 10 is shown below.

(10-1) Synthesis of Intermediate (J)

Under argon atmosphere, 56.3 g of 1,4-dibromo-2-fluorobenzene, 43.8 g ofcopper cyanide (I) and 500 mL of dimethylsulphoxide were put into aflask and heated at 115 degrees C. for 19 hours while being stirred.After cooled down to the room temperature, the reaction solution wasadded with ethyl acetate and water to be extracted. After an aqueouslayer was removed, an organic layer was washed with ammonia water. Afterdried with sodium sulfate, the organic layer was concentrated. Theobtained residue was refined by silica-gel column chromatography andfurther by recrystallization, whereby 16.3 g (yield 50%) of a whitesolid of an intermediate (J) was obtained. It should be noted thatdimethylsulphoxide is occasionally abbreviated as DMSO.

(10-2) Synthesis of Compound 10

A compound 10 was synthesized in the same manner as in the synthesis(1-3) of the compound 1, except for using the intermediate (I) in placeof the intermediate (A) and using the intermediate (J) in place of2,5-dichloroterephthalonitrile.

Example 11: Synthesis of Compound 11

A synthesis scheme of a compound 11 is shown below.

(11-1) Synthesis of Compound 11

A compound 11 was synthesized in the same manner as in the synthesis(1-3) of the compound 1, except for using the intermediate (B) in placeof the intermediate (A) and using the intermediate (H) in place of2,5-dichloroterephthalonitrile.

Second Evaluation of Compounds

Next, fluorescence spectra of the compounds 3 to 8 were measured toobtain a main peak wavelength λ_(F). A measurement method or calculationmethod was the same as the above. The measurement results or calculationresults are shown in Table 2.

As a result, it is revealed that the compounds 3 to 8 forming a cyclicstructure emits light in longer wavelength regions as compared with thereference compound 1 described above.

TABLE 2 λ_(F) (nm) Compound 1 512 Compound 2 541 Compound 3 509 Compound4 495 Compound 5 526 Compound 6 479 Compound 7 511 Compound 8 536Compound 9 500 Compound 10 536 Compound 11 505 Reference Compound 1 473Device Evaluation

Next, an organic el device was prepared and evaluated.

In addition to the above compounds, compounds used for preparing theorganic EL device were shown below.

Example 12: Preparation of Organic EL Device

A glass substrate (size: 25 mm×75 mm×1.1 mm thick, manufactured byGeomatec Co., Ltd.) having an ITO transparent electrode (anode) wasultrasonic-cleaned in isopropyl alcohol for five minutes, and thenUV/ozone-cleaned for 30 minutes. A film of ITO was 130 nm thick.

After the glass substrate having an ITO transparent electrode wascleaned, the glass substrate was mounted on a substrate holder of avacuum evaporation apparatus. Initially, a compound HI was deposited ona surface of the glass substrate where the transparent electrode linewas provided in a manner to cover the transparent electrode, therebyforming a 5-nm thick film of the compound HI. The HI film serves as ahole injecting layer.

After the film formation of the HI film, a compound HT-1 was depositedon the HI film to form a 20-nm thick HT-1 film. The HT-1 film serves asa hole transporting layer.

After the formation of the HT-1 film, a compound HT-2 was deposited onthe HT-1 film to form a 5-nm thick HT-2 film on the HT-1 film. The HT-2film also serves as a hole transporting layer.

After the formation of the HT-2 film, a compound CBP was deposited onthe HT-2 film to form a 5-nm thick CBP film on the HT-2 film. The CBPfilm also serves as a hole transporting layer.

Next, a compound PG-1 and the compound 1 were co-deposited to form a25-nm thick emitting layer on the CBP film. A mass ratio between thecompound PG-1 and the compound 1 was set at 76 mass %:24 mass %.

A compound EB-1 was deposited on the emitting layer to form a 5-nm thickhole blocking layer.

Further, a compound ET-1 was deposited on the EB-1 film to form a 50-nmthick ET-1 film. The ET-1 film serves as an electron transporting layer.

LiF was deposited on the electron transporting layer to form a 1-nmthick LiF film.

A metal Al was deposited on the LiF film to form an 80-nm thick metalcathode.

A device arrangement of the organic EL device in Example 12 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 1(25,76%:24%)/EB-1(5)/ET-1(50)/LiF (1)/Al(80)

Numerals in parentheses represent a film thickness (unit: nm). Thenumerals represented by percentage in parentheses indicate a ratio (mass%) of the compound in the layer. The same applies below.

Example 13: Preparation of Organic EL Device

An organic EL device in Example 13 was prepared in the same manner as inExample 12 except that the mass ratio between the compound PG-1 and thecompound 1 in the emitting layer of Example 12 was changed to 50 mass %:50 mass %.

A device arrangement of the organic EL device in Example 13 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 1 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 14: Preparation of Organic EL Device

An organic EL device in Example 14 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 2.

A device arrangement of the organic EL device in Example 14 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 2(25,76%:24%)/EB-1(5)/ET-1(50)/LiF (1)/Al(80)

Example 15: Preparation of Organic EL Device

An organic EL device in Example 15 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 2.

A device arrangement of the organic EL device in Example 15 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 2 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 16: Preparation of Organic EL Device

An organic EL device in Example 16 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 3.

A device arrangement of the organic EL device in Example 16 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 3(25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 17: Preparation of Organic EL Device

An organic EL device in Example 17 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 3.

A device arrangement of the organic EL device in Example 17 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 3 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 18: Preparation of Organic EL Device

An organic EL device in Example 18 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 4.

A device arrangement of the organic EL device in Example 18 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 4 (25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 19: Preparation of Organic EL Device

An organic EL device in Example 19 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 4.

A device arrangement of the organic EL device in Example 19 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 4 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 20: Preparation of Organic EL Device

An organic EL device in Example 20 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 5.

A device arrangement of the organic EL device in Example 20 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 5 (25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 21: Preparation of Organic EL Device

An organic EL device in Example 21 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 5.

A device arrangement of the organic EL device in Example 21 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 5 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 22: Preparation of Organic EL Device

An organic EL device in Example 22 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 6.

A device arrangement of the organic EL device in Example 22 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 6 (25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 23: Preparation of Organic EL Device

An organic EL device in Example 23 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 6.

A device arrangement of the organic EL device in Example 23 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 6 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 24: Preparation of Organic EL Device

An organic EL device in Example 24 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 7.

A device arrangement of the organic EL device in Example 24 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 7 (25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 25: Preparation of Organic EL Device

An organic EL device in Example 25 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 7.

A device arrangement of the organic EL device in Example 25 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 7 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 26: Preparation of Organic EL Device

An organic EL device in Example 26 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 8.

A device arrangement of the organic EL device in Example 26 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 8 (25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 27: Preparation of Organic EL Device

An organic EL device in Example 27 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 8.

A device arrangement of the organic EL device in Example 27 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 8 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 28: Preparation of Organic EL Device

An organic EL device in Example 28 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 9.

A device arrangement of the organic EL device in Example 28 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 9 (25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 29: Preparation of Organic EL Device

An organic EL device in Example 29 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 9.

A device arrangement of the organic EL device in Example 29 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 9 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 30: Preparation of Organic EL Device

An organic EL device in Example 30 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 10.

A device arrangement of the organic EL device in Example 30 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 10 (25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 31: Preparation of Organic EL Device

An organic EL device in Example 31 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 10.

A device arrangement of the organic EL device in Example 31 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 10 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 32: Preparation of Organic EL Device

An organic EL device in Example 32 was prepared in the same manner as inExample 12 except that the compound 1 in the emitting layer of Example12 was changed to the compound 11.

A device arrangement of the organic EL device in Example 32 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 11 (25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Example 33: Preparation of Organic EL Device

An organic EL device in Example 33 was prepared in the same manner as inExample 13 except that the compound 1 in the emitting layer of Example13 was changed to the compound 11.

A device arrangement of the organic EL device in Example 33 is roughlyshown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Compound 11 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Comparative 1: Preparation of Organic EL Device

An organic EL device in Comparative 1 was prepared in the same manner asin Example 12 except that the compound 1 in the emitting layer ofExample 12 was changed to the compound 1.

A device arrangement of the organic EL device in Comparative 1 isroughly shown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Reference Compound 1 (25,76%:24%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Comparative 2: Preparation of Organic EL Device

An organic EL device in Comparative 2 was prepared in the same manner asin Example 13 except that the compound 1 in the emitting layer ofExample 13 was changed to the compound 1.

A device arrangement of the organic EL device in Comparative 2 isroughly shown as follows.

ITO(130)/HI(5)/HT-1(20)/HT-2(5)/CBP(5)/PG-1: Reference Compound 1 (25,50%:50%)/EB-1(5)/ET-1(50)/LiF(1)/Al(80)

Evaluation of Organic EL Devices

The prepared organic EL devices of Examples 12 to 33 and Comparatives 1to 2 were evaluated as follows. The results are shown in Table 3.

Luminous Intensity

Voltage was applied on each of the organic EL devices such that thecurrent density was 10.0 mA/cm², where a luminous intensity was measuredusing a spectroradiometer CS-1000 (manufactured by Konica Minolta,Inc.).

Main Peak Wavelength λ_(p)

Voltage was applied on each of the organic EL devices such that thecurrent density was 10.0 mA/cm², where spectral radiance spectra weremeasured by a spectroradiometer CS-1000 (manufactured by Konica Minolta,Inc). Based on the obtained spectral radiance spectra, a main peakwavelength λ_(p) was calculated. The main peak wavelength λ_(p) is apeak wavelength at which the luminous intensity in the spectra reachesthe maximum.

Delayed Fluorescence Lifetime

Delayed fluorescence lifetime was measured and calculated using afluorescence lifetime spectrofluorometer (TemPro: manufactured HORIBA,Ltd). The prepared organic EL devices of Examples 12 to 33 andComparatives 1 to 2 were used as measurement samples.

A semiconductor pulse LED light source NanoLED-340 or a semiconductorpulse LED light source SpectralLED-355 were used as an excitation lightsource. The excitation light source was selectively used depending onthe delayed fluorescence lifetime. A spectral wavelength obtained by adetector PPD-850 of the fluorescence lifetime spectrofluorometer wasdefined as the main peak wavelength λ_(p) of each of the organic ELdevices of Examples 12 to 33 and Comparatives 1 to 2. The measurementwas conducted at the room temperature.

TABLE 3 Luminous Main peak Delayed Emitting layer Intensicy wavelengthfluorescence Compound Mass ratio (nit) λ_(P) (nm) lifetime (μs) Example12 PG-1:Compound 1 76%:24% 1164.1 569 2.82 Example 13 PG-1:Compound 150%:50% 670.6 581 2.31 Example 14 PG-1:Compound 2 76%:24% 1004.6 5752.26 Example 15 PG-1:Compound 2 50%:50% 552.4 586 1.50 Example 16PG-1:Compound 3 76%:24% 1914.2 560 7.72 Example 17 PG-1:Compound 350%:50% 1390.0 567 6.94 Example 18 PG-1:Compound 4 76%:24% 3437.6 54513.50 Example 19 PG-1:Compound 4 50%:50% 3368.3 550 12.00 Example 20PG-1:Compound 5 76%:24% 876.3 567 5.20 Example 21 PG-1:Compound 550%:50% 680.8 581 6.55 Example 22 PG-1:Compound 6 76%:24% 2464.4 52923.10 Example 23 PG-1:Compound 6 50%:50% 3202.0 538 26.30 Example 24PG-1:Compound 7 76%:24% 3938.5 551 10.10 Example 25 PG-1:Compound 750%:50% 3337.5 556 8.29 Example 26 PG-1:Compound 8 76%:24% 1817.9 5871.17 Example 27 PG-1:Compound 8 50%:50% 1068.1 599 1.06 Example 28PG-1:Compound 9 76%:24% 2252.0 564 12.30 Example 29 PG-1:Compound 950%:50% 2046.7 569 10.00 Example 30 PG-1:Compound 10 76%:24% 704.2 5773.22 Example 31 PG-1:Compound 10 50%:50% 440.3 586 2.12 Example 32PG-1:Compound 11 76%:24% 2215.0 546 22.50 Example 33 PG-1:Compound 1150%:50% 1941.3 555 9.70 Comp. 1 PG-1:Reference Compound 1 76%:24% 2613.5520 58.60 Comp. 2 PG-1:Reference Compound 1 50%:50% 1950.9 529 48.30

As shown in the above Table, it is found that the organic EL devicesusing the compounds 1 to 11 have main peak wavelengths in a longerwavelength as compared with the organic EL device using the referencecompound 1.

As shown in the above Table, it is confirmed from the values of thedelayed fluorescence lifetime of the organic EL devices in Examples 12to 33 that the compounds 1 to 11 are compounds emitting delayedfluorescence.

EXPLANATION OF CODE(S)

-   -   1 . . . organic EL device, 2 . . . substrate, 3 . . . anode, . .        . cathode, 5 . . . emitting layer, 6 . . . holes        injecting/transporting layer, 7 . . . electrons        injecting/transporting layer, 10 . . . organic layer.

The invention claimed is:
 1. A compound represented by a formula (40):

where: k is an integer of 0 to 2, m is an integer of 2 to 4, n is aninteger of 2 to 4, q is an integer of 0 to 2, and k+m+n+q=6, and CN is acyano group, and R_(x) each independently is a hydrogen atom, asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted heterocyclic group having 6 to 30ring atoms, a substituted or unsubstituted alkyl group having 1 to 30carbon atoms, a substituted or unsubstituted alkylsilyl group having 3to 30 carbon atoms, or a substituted or unsubstituted arylsilyl grouphaving 6 to 60 ring carbon atoms, and D₁ is represented by one offormulae (3) and (3x) below, D₂ is represented by one of the formulae(3), (3x) below and formulae (33) to (38) below, D₁ and D₂ beingoptionally the same or different, a plurality of D₁ being optionally thesame or different, a plurality of D₂ being optionally the same ordifferent,

R₁₁ to R₁₈ of the formula (3), and R₁₁₁ to R₁₁₈ of the formula (3x) eachindependently represent a hydrogen atom, a substituted or unsubstitutedaryl group having 6 to 30 ring carbon atoms, a substituted orunsubstituted heterocyclic group having 5 to 30 ring atoms, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkylsilyl group having 3 to 30 carbonatoms, a substituted or unsubstituted arylsilyl group having 6 to 60ring carbon atoms, a substituted or unsubstituted alkoxy group having 1to 30 carbon atoms, a substituted or unsubstituted aryloxy group having6 to 30 ring carbon atoms, a substituted or unsubstituted alkylaminogroup having 2 to 30 carbon atoms, a substituted or unsubstitutedarylamino group having 6 to 60 ring carbon atoms, a substituted orunsubstituted alkylthio group having 1 to 30 carbon atoms, or asubstituted or unsubstituted arylthio group having 6 to 30 ring carbonatoms, in the formula (3), at least one of combinations of substituentsselected from R₁₁ to R₁₈ is optionally mutually bonded to form a cyclicstructure, in the formula (3x), at least one of combinations ofsubstituents selected from R₁₁₁ to R₁₁₈ is optionally mutually bonded toform a cyclic structure, in the formulae (3) and (3x): A, B and C eachindependently represent a cyclic structure represented by one of aformula (31) and a formula (32) below, each of the cyclic structure A,cyclic structure B, and cyclic structure C being fused with its adjacentcyclic structures at any positions, p is 4, and four cyclic structures Ainclude two cyclic structures represented by the formula (31) and twocyclic structures represented by the formula (32), and px and py areeach 2, two cyclic structures B include one cyclic structure representedby the formula (31) and one cyclic structure represented by the formula(32), and two cyclic structures C include one cyclic structurerepresented by the formula (31) and one cyclic structure represented bythe formula (32),

in the formula (31), R₁₉ and R₂₀ each independently represent the sameas R₁₁ to R₁₈ and are optionally mutually bonded to form a cyclicstructure, and in the formula (32): X₁ represents a sulfur atom, or anoxygen atom, and at least one X₁ in the formulae (3) and (3x) for D₁ isa sulfur atom,

in the formulae (33) to (38), R₁₁ to R₂₀ each independently represent ahydrogen atom, a substituted or unsubstituted aryl group having 6 to 30ring carbon atoms, a substituted or unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, a substituted or unsubstituted alkyl grouphaving 1 to 30 carbon atoms, a substituted or unsubstituted alkylsilylgroup having 3 to 30 carbon atoms, a substituted or unsubstitutedarylsilyl group having 6 to 60 ring carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 30 carbon atoms, a substituted orunsubstituted aryloxy group having 6 to 30 ring carbon atoms, asubstituted or unsubstituted alkylamino group having 2 to 30 carbonatoms, a substituted or unsubstituted arylamino group having 6 to 60ring carbon atoms, a substituted or unsubstituted alkylthio group having1 to 30 carbon atoms, or a substituted or unsubstituted arylthio grouphaving 6 to 30 ring carbon atoms; and at least one of combinations ofsubstituents selected from R₁₁ to R₂₀ are optionally mutually bonded toform a cyclic structure, and X₁ in the formulae (33) to (38) representsa sulfur atom or an oxygen atom.
 2. The compound according to claim 1,wherein D₁ is represented by the formula (3).
 3. The compound accordingto claim 1, wherein D₁ is represented by the formula (3x).
 4. Thecompound according to claim 1, wherein the formula (3x) is representedby a formula (3y) below,

in the formula (3y), R₁₁₁ to R₁₁₈ each independently represent the sameas R₁₁₁ to R₁₁₈ described in the formula (3x), one of a cyclic structureB1 and a cyclic structure B2 is the cyclic structure represented by theformula (31), and the other of the cyclic structure B1 and the cyclicstructure B2 is the cyclic structure represented by the formula (32),and one of a cyclic structure C1 and a cyclic structure C2 is the cyclicstructure represented by the formula (31), and the other of the cyclicstructure C1 and the cyclic structure C2 is the cyclic structurerepresented by the formula (32).
 5. The compound according to claim 4,wherein in the formula (3y), the cyclic structure B1 and the cyclicstructure C1 are each independently the cyclic structure represented bythe formula (31) and the cyclic structure B2 and the cyclic structure C2are each independently the cyclic structure represented by the formula(32).
 6. The compound according to claim 1, wherein R_(X), R₁₁ to R₂₀and R₁₁₁ to R₁₁₈ are each independently selected from the groupconsisting of a hydrogen atom, a substituted or unsubstituted aryl grouphaving 6 to 20 ring carbon atoms, a substituted or unsubstitutedheterocyclic group having 5 to 14 ring atoms, a substituted orunsubstituted alkyl group having 1 to 6 carbon atoms, a substituted orunsubstituted alkylsilyl group having 3 to 30 carbon atoms, asubstituted or unsubstituted arylsilyl group having 6 to 60 ring carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aryloxy group having 6 to 30 ringcarbon atoms, a substituted or unsubstituted alkylamino group having 2to 30 carbon atoms, a substituted or unsubstituted arylamino grouphaving 6 to 60 ring carbon atoms, a substituted or unsubstitutedalkylthio group having 1 to 30 carbon atoms, and a substituted orunsubstituted arylthio group having 6 to 30 ring carbon atoms, anysubstituents of the substituent(s) are selected from the groupconsisting of a hydrogen atom, an aryl group having 6 to 20 ring carbonatoms, a heterocyclic group having 5 to 14 ring atoms, an alkyl grouphaving 1 to 6 carbon atoms, an alkylsilyl group having 3 to 30 carbonatoms, an arylsilyl group having 6 to 60 ring carbon atoms, an alkoxygroup having 1 to 30 carbon atoms, an aryloxy group having 6 to 30 ringcarbon atoms, an alkylamino group having 2 to 30 carbon atoms, anarylamino group having 6 to 60 ring carbon atoms, an alkylthio grouphaving 1 to 30 carbon atoms, and an arylthio group having 6 to 30 ringcarbon atoms.
 7. The compound according to claim 1, wherein R₁₁ to R₂₀are not mutually bonded to form a cyclic structure, R₁₁₁ to R₁₁₈ are notmutually bonded to form a cyclic structure, and R₁₁ to R₂₀ and R₁₁₁ toR₁₁₈ are each independently a hydrogen atom, an unsubstituted aryl grouphaving 6 to 30 ring carbon atoms, an unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, or an unsubstituted alkyl group having 1 to30 carbon atoms.
 8. The compound according to claim 1, wherein thecompound is represented by a formula (4) below:

where: k is an integer of 0 to 2, m is an integer of 2 to 4, n is aninteger of 2 to 4, q is an integer of Oto 2, and k+m+n+q=6; R₄₀ is eachindependently a hydrogen atom, a substituted or unsubstituted aryl grouphaving 6 to 30 ring carbon atoms, a substituted or unsubstituted alkylgroup having 1 to 30 carbon atoms, a substituted or unsubstitutedalkylsilyl group having 3 to 30 carbon atoms, or a substituted orunsubstituted arylsilyl group having 6 to 60 ring carbon atoms, aplurality of R₄₀ being optionally mutually the same or different; D₁ andD₂ each independently represent the same as D₁ and D₂ of the formula(40), a plurality of D₁ being optionally mutually the same or different,a plurality of D₂ being optionally mutually the same or different; andR₄₀, D₁, D₂ and CN are respectively bonded to carbon atoms forming abenzene ring.
 9. The compound according to claim 8, wherein the compoundis represented by one of formulae (41) to (43) below:

where: k is an integer of 0 to 2, m is an integer of 2 to 4, q is aninteger of 0 to 2, and k+m+q=4, and D₁, D₂ and R₄₀ are as defined inclaim
 8. 10. The compound according to claim 9, wherein the compound isrepresented by the formula (43).
 11. The compound according to claim 8,wherein R₄₀, R₁₁ to R₂₀ and R₁₁₁ to R₁₁₈ are each independently selectedfrom the group consisting of a hydrogen atom, a substituted orunsubstituted aryl group having 6 to 20 ring carbon atoms, a substitutedor unsubstituted alkyl group having 1 to 6 carbon atoms, a substitutedor unsubstituted alkylsilyl group having 3 to 30 carbon atoms, and asubstituted or unsubstituted arylsilyl group having 6 to 60 ring carbonatoms, and any substituents of said substituent(s) are selected from thegroup consisting of a hydrogen atom, an aryl group having 6 to 20 ringcarbon atoms, a heterocyclic group having 5 to 14 ring atoms, an alkylgroup having 1 to 6 carbon atoms, an alkylsilyl group having 3 to 30carbon atoms, an arylsilyl group having 6 to 60 ring carbon atoms, analkoxy group having 1 to 30 carbon atoms, an aryloxy group having 6 to30 ring carbon atoms, an alkylamino group having 2 to 30 carbon atoms,an arylamino group having 6 to 60 ring carbon atoms, an alkylthio grouphaving 1 to 30 carbon atoms, and an arylthio group having 6 to 30 ringcarbon atoms.
 12. The compound according to claim 8, wherein R₁₁ to R₂₀are not mutually bonded to form a cyclic structure; R₁₁₁ to R₁₁₈ are notmutually bonded to form a cyclic structure; and R₁₁ to R₂₀ and R₁₁₁ toR₁₁₈ are each independently a hydrogen atom, an unsubstituted aryl grouphaving 6 to 30 ring carbon atoms, an unsubstituted heterocyclic grouphaving 5 to 30 ring atoms, or an unsubstituted alkyl group having 1 to30 carbon atoms.
 13. An organic-electroluminescence-device materialcomprising the compound according to claim
 1. 14. An organicelectroluminescence device comprising: an anode; a cathode; and one ormore organic layers interposed between the anode and the cathode,wherein at least one of the organic layers comprises the compoundaccording to claim
 1. 15. Electronic equipment comprising the organicelectroluminescence device according to claim 14.